Counter electrode for electrochromic devices

ABSTRACT

The embodiments herein relate to electrochromic stacks, electrochromic devices, and methods and apparatus for making such stacks and devices. In various embodiments, an anodically coloring layer in an electrochromic stack or device is fabricated to include nickel-tungsten-niobium-oxide (NiWNbO). This material is particularly beneficial in that it is very transparent in its clear state.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S.application Ser. No. 15/526,969, filed May 15, 2017, and titled “COUNTERELECTRODE FOR ELECTROCHROMIC DEVICES,” which is a § 371 National Phaseapplication of PCT Application No. PCT/US15/61668, filed Nov. 19, 2015,and titled “COUNTER ELECTRODE FOR ELECTROCHROMIC DEVICES,” which claimsbenefit of priority to U.S. Provisional Application No. 62/085,098,filed Nov. 26, 2014, and titled “COUNTER ELECTRODE FOR ELECTROCHROMICDEVICES,” and to U.S. Provisional Application No. 62/192,443, filed Jul.14, 2015, and titled “COUNTER ELECTRODE FOR ELECTROCHROMIC DEVICES,”each of which is herein incorporated by reference in its entirety andfor all purposes.

BACKGROUND

Electrochromism is a phenomenon in which a material exhibits areversible electrochemically-mediated change in an optical property whenplaced in a different electronic state, typically by being subjected toa voltage change. The optical property is typically one or more ofcolor, transmittance, absorbance, and reflectance. One well knownelectrochromic material, for example, is tungsten oxide (WO₃). Tungstenoxide is a cathodic electrochromic material in which a colorationtransition, transparent to blue, occurs by electrochemical reduction.Anodic electrochromic materials are also known, e.g., nickel oxide (e.g.NiO).

Electrochromic materials may be incorporated into, for example, windowsand mirrors. The color, transmittance, absorbance, and/or reflectance ofsuch windows and mirrors may be changed by inducing a change in theelectrochromic material. One well known application of electrochromicmaterials, for example, is electrochromic windows for buildings.

While electrochromism was discovered in the 1960's, electrochromicdevices have historically suffered from various problems that haveprevented the technology from realizing its full commercial potential.For example, electrochromic windows may use tungsten oxide and/or nickeloxide materials, but there is much room for improvement. Certain areasthat can be improved include material stability over time, switchingspeed, and optical properties, e.g., tinted states are often too blueand transparent states are often too yellow.

SUMMARY

The embodiments herein relate to electrochromic materials,electrochromic stacks, electrochromic devices, as well as methods andapparatus for making such materials, stacks, and devices. In variousembodiments, a counter electrode material includes a novel compositionof materials including nickel, tungsten, niobium, and oxygen.

In one aspect of the disclosed embodiments, a method of fabricating anelectrochromic stack is provided, the method including: forming acathodically coloring layer including a cathodically coloringelectrochromic material; and forming an anodically coloring layerincluding nickel tungsten niobium oxide (NiWNbO). The NiWNbO materialmay meet have a particular composition. For example, in some cases, theNiWNbO has an atomic ratio of Ni:(W+Nb) that is between about 1.5:1 and3:1, or between about 1.5:1 and 2.5:1, or between about 1.8:1 and 2.5:1,or between about 2:1 and 2.5:1, or between about 2:1 and 3:1. In theseor other cases, the NiWNbO may have an atomic ratio of W:Nb that isbetween about 0.1:1 and 6:1, or between about 0.2:1 and 5:1, or betweenabout 0.2:1 and 1:1, or between about 1:1 and 2:1.

The anodically coloring layer may be formed by sputtering one or moresputter targets to form the NiWNbO. At least one of the one or more ofthe sputter targets may include an elemental metal selected from thegroup consisting of: nickel, tungsten, and niobium. In some cases, atleast one of the one or more of the sputter targets may include an alloyincluding two or more metals selected from the group consisting of:nickel, tungsten, and niobium. At least one of the one or more sputtertargets may include an oxide in some cases. In various embodiments, theanodically coloring layer may be substantially amorphous.

The cathodically coloring layer and the anodically coloring layer may beformed in direct physical contact with one another, without a separatelydeposited ion conductor layer between them. In some implementations, theanodically coloring layer includes two or more sub-layers that havedifferent compositions and/or morphologies. In certain embodiments thecathodically coloring electrochromic material includes tungsten oxide(WO_(x)). In some such cases, x may be less than 3.0. In these or othercases, x may be at least about 2.7. In various implementations, thecathodically coloring layer may include a bilayer or a graded layer, anda portion of the cathodically coloring layer may be superstoichiometricwith respect to oxygen.

In another aspect of the disclosed embodiments, an electrochromic stackis provided, the electrochromic stack including: a cathodically coloringlayer including a cathodically coloring material; and an anodicallycoloring layer including nickel tungsten niobium oxide (NiWNbO).

The NiWNbO may have a particular composition in some cases. Forinstance, the NiWNbO may an atomic ratio of Ni:(W+Nb) that is betweenabout 1.5:1 and 3:1, or between about 1.5:1 and 2.5:1, or between about1.8:1 and 2.5:1, or between about 2:1 and 2.5:1, or between about 2:1and 3:1. In these or other cases, the NiWNbO may have an atomic ratio ofW:Nb that is between about 0.1:1 and 6:1, or between about 0.2:1 and5:1, or between about 0.2:1 and 1:1, or between about 1:1 and 2:1. Theanodically coloring layer may be substantially amorphous. In some cases,the anodically coloring layer may include an amorphous matrix of a firstmaterial having domains of a second material scattered throughout theamorphous matrix.

The cathodically coloring layer may be in direct physical contact withthe anodically coloring layer in some cases. In a number of embodiments,the anodically coloring layer may include two or more sub-layers havingdifferent compositions and/or morphologies. In certain embodiments thecathodically coloring material includes tungsten oxide (WO_(x)). In somesuch cases, x may be less than 3.0. In these or other cases, x may be atleast about 2.7. In various implementations, the cathodically coloringlayer may include a bilayer or a graded layer, and a portion of thecathodically coloring layer may be superstoichiometric with respect tooxygen.

In a further aspect of the disclosed embodiments, an integrateddeposition system for fabricating an electrochromic stack is provided,the system including: a plurality of deposition stations aligned inseries and interconnected and operable to pass a substrate from onestation to the next without exposing the substrate to an externalenvironment, where the plurality of deposition stations include (i) afirst deposition station containing one or more material sources fordepositing a cathodically coloring layer; (ii) a second depositionstation containing one or more material sources for depositing ananodically coloring layer including nickel tungsten niobium oxide(NiWNbO); and a controller containing program instructions for passingthe substrate through the plurality of stations in a manner thatdeposits on the substrate (i) the cathodically coloring layer, and (ii)the anodically coloring layer to form a stack including at least thecathodically coloring layer and the anodically coloring layer.

The NiWNbO may be deposited to include a particular composition in somecases. For example, the NiWNbO may haves an atomic ratio of Ni:(W+Nb)that is between about 1.5:1 and 3:1, or between about 1.5:1 and 2.5:1,or between about 1.8:1 and 2.5:1, or between about 2:1 and 2.5:1, orbetween about 2:1 and 3:1. In these or other cases, the NiWNbO may havean atomic ratio of W:Nb that is between about 0.1:1 and 6:1, or betweenabout 0.2:1 and 5:1, or between about 0.2:1 and 1:1, or between about1:1 and 2:1.

In certain implementations, at least one of the one or more materialsources for depositing the anodically coloring layer include anelemental metal selected from the group consisting of: nickel, tungsten,and niobium. In these or other implementations, at least one of the oneor more material sources for depositing the anodically coloring layerinclude an alloy including two or more metals selected from the groupconsisting of: nickel, tungsten, and niobium. In some embodiments, atleast one of the one or more material sources for depositing theanodically coloring layer include an oxide. The anodically coloringlayer may be deposited to include a particular morphology in some cases.For instance, the deposition system may be configured to deposit theanodically coloring layer as a substantially amorphous material.

In these or other cases, the integrated deposition system may beconfigured to deposit the cathodically coloring layer and the anodicallycoloring layer in direct physical contact with one another. Further, theanodically coloring layer may be deposited to include a particularstructure. In some embodiments, for instance, the controller may containprogram instructions for depositing the anodically coloring layer as twoor more sub-layers having different compositions and/or morphologies.The sub-layers of the anodically coloring layer may all be deposited inthe second deposition station, though in some cases one or moresub-layers of the anodically coloring layer may be deposited in a thirddeposition station. In certain embodiments the cathodically coloringlayer includes tungsten oxide (WO_(x)). In some such cases, x may beless than 3.0. In these or other cases, x may be at least about 2.7. Invarious implementations, the cathodically coloring layer may include abilayer or a graded layer, and a portion of the cathodically coloringlayer may be superstoichiometric with respect to oxygen.

In a further aspect of the disclosed embodiments, a composition ofmatter is provided, including: (a) nickel; (b) tungsten; (c) niobium;and (d) oxygen, where the composition includes an atomic ratio ofNi:(W+Nb) that is between about 1.5:1 and 3:1, and an atomic ratio ofW:Nb that is between about 0.1:1 and 6:1.

In certain embodiments, the atomic ratio of Ni:(W+Nb) may be betweenabout 1.5:1 and 3:1, or between about 1.5:1 and 2.5:1, or between about1.8:1 and 2.5:1, or between about 2:1 and 2.5:1, or between about 2:1and 3:1. In these or other embodiments, the atomic ratio of W:Nb may bebetween about 0.1:1 and 6:1, or between about 0.2:1 and 5:1, or betweenabout 0.2:1 and 1:1, or between about 1:1 and 2:1. The composition maybe provided in a layer having a thickness between about 50-650 nm. Thecomposition may be formed through sputtering one or more sputtertargets. In various embodiments, the composition becomes tinted inresponse to an applied anodic potential.

In some implementations, the composition is amorphous. In some cases,the composition is provided as an amorphous matrix with nanocrystalsdistributed throughout. The nanocrystals may have a mean diameter ofabout 50 nm or less, in some cases a mean diameter between about 1-10.

These and other features and advantages of the disclosed embodimentswill be described in further detail below, with reference to theassociated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description can be more fully understood whenconsidered in conjunction with the drawings in which:

FIGS. 1A-1C present schematic cross-sections of electrochromic devicesin accordance with certain embodiments.

FIGS. 1D-1G are graphs describing the composition of a heterogeneouscounter electrode layer in accordance with certain embodiments.

FIG. 2 depicts a cross-sectional representation of an electrochromicwindow device in accord with the multistep process description providedin relation to FIG. 4A.

FIG. 3 depicts a top view of an electrochromic device showing locationof trenches cut into the device.

FIG. 4A depicts a process flow describing a method of fabricating anelectrochromic window.

FIGS. 4B-4D depict methods of fabricating an electrochromic stack whichis part of an electrochromic device according to certain embodiments.

FIG. 4E depicts a process flow for a conditioning process used tofabricate an electrochromic device according to certain embodiments.

FIG. 5A, depicts an integrated deposition system according to certainembodiments.

FIG. 5B depicts an integrated deposition system in a perspective view.

FIG. 5C depicts a modular integrated deposition system.

FIG. 5D depicts an integrated deposition system with two lithiumdeposition stations.

FIG. 5E depicts an integrated deposition system with one lithiumdeposition station.

FIG. 6A illustrates a rotating sputter target according to certainembodiments.

FIG. 6B shows a top-down view of two rotating sputter targets depositingmaterial on a substrate according to certain embodiments.

FIGS. 7A-7C relate to embodiments where a secondary sputter target isused to deposit material onto a primary sputter target, which thendeposits on a substrate according to certain embodiments.

FIG. 8 illustrates a hysteresis curve for depositing various opticallyswitchable materials.

DETAILED DESCRIPTION

Electrochromic Devices

A schematic cross-section of an electrochromic device 100 in accordancewith some embodiments is shown in FIG. 1A. The electrochromic deviceincludes a substrate 102, a conductive layer (CL) 104, an electrochromiclayer (EC) 106 (sometimes also referred to as a cathodically coloringlayer), an ion conducting layer (IC) 108, a counter electrode layer (CE)110 (sometimes also referred to as an anodically coloring layer), and aconductive layer (CL) 114. Elements 104, 106, 108, 110, and 114 arecollectively referred to as an electrochromic stack 120. In certainimplementations, a heterogeneous counter electrode may be used, asdescribed in relation to FIGS. 1B-1G, below.

A voltage source 116 operable to apply an electric potential across theelectrochromic stack 120 effects the transition of the electrochromicdevice from, e.g., a clear state to a tinted state. In otherembodiments, the order of layers is reversed with respect to thesubstrate. That is, the layers are in the following order: substrate,conductive layer, counter electrode layer, ion conducting layer,electrochromic material layer, conductive layer.

It should be understood that the reference to a transition between aclear state and tinted state is non-limiting and suggests only oneexample, among many, of an electrochromic transition that may beimplemented. Unless otherwise specified herein, whenever reference ismade to a clear-tinted transition, the corresponding device or processencompasses other optical state transitions such asnon-reflective-reflective, transparent-opaque, etc. Further the terms“clear” and “bleached” refer to an optically neutral state, e.g.,untinted, transparent or translucent. Still further, unless specifiedotherwise herein, the “color” or “tint” of an electrochromic transitionis not limited to any particular wavelength or range of wavelengths. Asunderstood by those of skill in the art, the choice of appropriateelectrochromic and counter electrode materials governs the relevantoptical transition. In various embodiments herein, a counter electrodeis fabricated to include nickel, tungsten, niobium, and oxygen,sometimes referred to as nickel tungsten niobium oxide or NiWNbO. Theindividual elements may be present at varying levels/concentrations. Incertain embodiments, for instance, a NiWNbO counter electrode may have acomposition that falls within the various composition ranges disclosedherein.

In certain embodiments, the electrochromic device reversibly cyclesbetween a clear state and a tinted state. In the clear state, apotential is applied to the electrochromic stack 120 such that availableions in the stack that can cause the electrochromic material 106 to bein the tinted state reside primarily in the counter electrode 110. Whenthe potential on the electrochromic stack is reversed, the ions aretransported across the ion conducting layer 108 to the electrochromicmaterial 106 and cause the material to enter the tinted state.

In certain embodiments, all of the materials making up electrochromicstack 120 are inorganic, solid (i.e., in the solid state), or bothinorganic and solid. Because organic materials tend to degrade overtime, inorganic materials offer the advantage of a reliableelectrochromic stack that can function for extended periods of time.Materials in the solid state also offer the advantage of not havingcontainment and leakage issues, as materials in the liquid state oftendo. Each of the layers in the electrochromic device is discussed indetail, below. It should be understood that any one or more of thelayers in the stack may contain some amount of organic material, but inmany implementations one or more of the layers contains little or noorganic matter. The same can be said for liquids that may be present inone or more layers in small amounts. It should also be understood thatsolid state material may be deposited or otherwise formed by processesemploying liquid components such as certain processes employing sol-gelsor chemical vapor deposition.

Referring again to FIG. 1A, voltage source 116 is typically a lowvoltage electrical source and may be configured to operate inconjunction with radiant and other environmental sensors. Voltage source116 may also be configured to interface with an energy managementsystem, such as a computer system that controls the electrochromicdevice according to factors such as the time of year, time of day, andmeasured environmental conditions. Such an energy management system, inconjunction with large area electrochromic devices (i.e., anelectrochromic window), can dramatically lower the energy consumption ofa building.

Any material having suitable optical, electrical, thermal, andmechanical properties may be used as substrate 102. Such substratesinclude, for example, glass, plastic, and mirror materials. Suitableplastic substrates include, for example acrylic, polystyrene,polycarbonate, allyl diglycol carbonate, SAN (styrene acrylonitrilecopolymer), poly(4-methyl-1-pentene), polyester, polyamide, etc. If aplastic substrate is used, it is preferably barrier protected andabrasion protected using a hard coat of, for example, a diamond-likeprotection coating, a silica/silicone anti-abrasion coating, or thelike, such as is well known in the plastic glazing art. Suitable glassesinclude either clear or tinted soda lime glass, including soda limefloat glass. The glass may be tempered or untempered. In someembodiments of electrochromic device 100 with glass, e.g. soda limeglass, used as substrate 102, there is a sodium diffusion barrier layer(not shown) between substrate 102 and conductive layer 104 to preventthe diffusion of sodium ions from the glass into conductive layer 104.

In some embodiments, the optical transmittance (i.e., the ratio oftransmitted radiation or spectrum to incident radiation or spectrum) ofsubstrate 102 is about 40 to 95%, e.g., about 90-92%. The substrate maybe of any thickness, as long as it has suitable mechanical properties tosupport the electrochromic stack 120. While the substrate 102 may be ofany size, in some embodiments, it is about 0.01 mm to 10 mm thick,preferably about 3 mm to 9 mm thick.

In some embodiments, the substrate is architectural glass. Architecturalglass is glass that is used as a building material. Architectural glassis typically used in commercial buildings, but may also be used inresidential buildings, and typically, though not necessarily, separatesan indoor environment from an outdoor environment. In certainembodiments, architectural glass is at least 20 inches by 20 inches, andcan be much larger, e.g., as large as about 72 inches by 120 inches.Architectural glass is typically at least about 2 mm thick.Architectural glass that is less than about 3.2 mm thick cannot betempered. In some embodiments with architectural glass as the substrate,the substrate may still be tempered even after the electrochromic stackhas been fabricated on the substrate. In some embodiments witharchitectural glass as the substrate, the substrate is a soda lime glassfrom a tin float line.

On top of substrate 102 is conductive layer 104. In certain embodiments,one or both of the conductive layers 104 and 114 is inorganic and/orsolid. Conductive layers 104 and 114 may be made from a number ofdifferent materials, including conductive oxides, thin metalliccoatings, conductive metal nitrides, and composite conductors.Typically, conductive layers 104 and 114 are transparent at least in therange of wavelengths where electrochromism is exhibited by theelectrochromic layer. Transparent conductive oxides include metal oxidesand metal oxides doped with one or more metals. Examples of such metaloxides and doped metal oxides include indium oxide, indium tin oxide,doped indium oxide, tin oxide, doped tin oxide, zinc oxide, aluminumzinc oxide, doped zinc oxide, ruthenium oxide, doped ruthenium oxide andthe like.

Since oxides are often used for these layers, they are sometimesreferred to as “transparent conductive oxide” (TCO) layers. Thinmetallic coatings that are substantially transparent may also be used.Examples of metals used for such thin metallic coatings includetransition metals including gold, platinum, silver, aluminum, nickelalloy, and the like. Thin metallic coatings based on silver, well knownin the glazing industry, are also used. Examples of conductive nitridesinclude titanium nitrides, tantalum nitrides, titanium oxynitrides, andtantalum oxynitrides. The conductive layers 104 and 114 may also becomposite conductors. Such composite conductors may be fabricated byplacing highly conductive ceramic and metal wires or conductive layerpatterns on one of the faces of the substrate and then over-coating withtransparent conductive materials such as doped tin oxides or indium tinoxide. Ideally, such wires should be thin enough as to be invisible tothe naked eye (e.g., about 100 μm or thinner).

In some embodiments, commercially available substrates such as glasssubstrates contain a transparent conductive layer coating. Such productsmay be used for both substrate 102 and conductive layer 104. Examples ofsuch glasses include conductive layer coated glasses sold under thetrademark TEC Glass™ by Pilkington, of Toledo, Ohio and SUNGATE™ 300 andSUNGATE™ 500 by PPG Industries of Pittsburgh, Pa. TEC Glass™ is a glasscoated with a fluorinated tin oxide conductive layer. In otherembodiments the substrate may be annealed glass, e.g. thin glass made byCorning, Inc. of Corning N.Y., such as Gorilla Glass™, Willow Glass™,Eagle Glass™ and the like.

In some embodiments, the same conductive layer is used for bothconductive layers (i.e., conductive layers 104 and 114). In someembodiments, different conductive materials are used for each conductivelayer 104 and 114. For example, in some embodiments, TEC Glass™ is usedfor substrate 102 (float glass) and conductive layer 104 (fluorinatedtin oxide) and indium tin oxide is used for conductive layer 114. Asnoted above, in some embodiments employing TEC Glass™ there is a sodiumdiffusion barrier between the glass substrate 102 and TEC conductivelayer 104. Some glasses are low sodium and do not require a sodiumdiffusion barrier.

The function of the conductive layers is to spread an electric potentialprovided by voltage source 116 over surfaces of the electrochromic stack120 to interior regions of the stack, with very little ohmic potentialdrop. The electric potential is transferred to the conductive layersthough electrical connections to the conductive layers. In someembodiments, bus bars, one in contact with conductive layer 104 and onein contact with conductive layer 114, provide the electric connectionbetween the voltage source 116 and the conductive layers 104 and 114.The conductive layers 104 and 114 may also be connected to the voltagesource 116 with other conventional means.

In some embodiments, the thickness of conductive layers 104 and 114 isbetween about 5 nm and about 10,000 nm. In some embodiments, thethickness of conductive layers 104 and 114 are between about 10 nm andabout 1,000 nm. In other embodiments, the thickness of conductive layers104 and 114 are between about 10 nm and about 500 nm.

The thickness of the each conductive layer 104 and 114 is alsosubstantially uniform. Smooth layers (i.e., low roughness, Ra) of theconductive layer 104 are desirable so that other layers of theelectrochromic stack 120 are more compliant. The sheet resistance(R_(s)) of the conductive layers is also important because of therelatively large area spanned by the layers. In some embodiments, thesheet resistance of conductive layers 104 and 114 is about 1 to 30 Ohmsper square. In some embodiments, the sheet resistance of conductivelayers 104 and 114 is about 15 Ohms per square. In general, it isdesirable that the sheet resistance of each of the two conductive layersbe about the same. In one embodiment, the two layers each have a sheetresistance of about 10-15 Ohms per square. In certain embodimentsconductive layers may be themselves stack structures, e.g., a stack oftransparent conductive oxide/metal/transparent conductive oxide, e.g.,ITO/Ag/ITO and similar transparent conductive layers known to skilledartisans. In such layers, e.g., the metal inner layer is typically thinenough so as to be transparent, e.g., between about 0.5 nm and about 20nm thick, or between about 1 nm and about 10 nm thick, or between about1 nm and about 5 nm thick. The metal interlayer, e.g., silver, may bedoped with other metals to increase its flexibility and/or ductility,e.g., silver interlayers may be doped with bismuth, beryllium and/orother metals. Such dopants may be, e.g., between about 1% to 25% byweight of the metal interlayer, e.g., between about 1% and about 20%,e.g., between about 1% and about 10%, e.g., between about 1% and about5%.

Overlaying conductive layer 104 is cathodically coloring layer 106 (alsoreferred to as electrochromic layer 106). In certain embodiments,electrochromic layer 106 is inorganic and/or solid, in typicalembodiments inorganic and solid. The electrochromic layer may containany one or more of a number of different cathodically coloringelectrochromic materials, including metal oxides. Such metal oxidesinclude, e.g., tungsten oxide (WO₃), molybdenum oxide (MoO₃), niobiumoxide (Nb₂O₅), titanium oxide (TiO₂), vanadium oxide (V₂O₅) and tantalumoxide (Ta₂O₅). In some embodiments, the cathodically coloring metaloxide is doped with one or more dopants such as lithium, sodium,potassium, molybdenum, vanadium, titanium, and/or other suitable metalsor compounds containing metals. Such dopants can be cathodicallycoloring, anodically coloring, or non-electrochromic, so long as thebulk material is cathodically coloring. For example, mixed oxides (e.g.,W—Mo oxide, W—V oxide) are also used in certain embodiments. Anelectrochromic layer 106 comprising a metal oxide is capable ofreceiving ions transferred from counter electrode layer 110.

In some embodiments, tungsten oxide or doped tungsten oxide is used forelectrochromic layer 106. In one embodiment, the electrochromic layer ismade substantially of WO_(x), where “x” refers to an atomic ratio ofoxygen to tungsten in the electrochromic layer, and x is between about2.7 and 3.5. It has been suggested that only sub-stoichiometric tungstenoxide exhibits electrochromism; i.e., stoichiometric tungsten oxide,WO₃, does not exhibit electrochromism. In a more specific embodiment,WO_(x), where x is less than 3.0 and at least about 2.7 is used for theelectrochromic layer. In another embodiment, the electrochromic layer isWOx, where x is between about 2.7 and about 2.9. Techniques such asRutherford Backscattering Spectroscopy (RBS) can identify the totalnumber of oxygen atoms which include those bonded to tungsten and thosenot bonded to tungsten. In some instances, tungsten oxide layers where xis 3 or greater exhibit electrochromism, presumably due to unboundexcess oxygen along with sub-stoichiometric tungsten oxide. In anotherembodiment, the tungsten oxide layer has stoichiometric or greateroxygen, where x is 3.0 to about 3.5.

In certain embodiments, the tungsten oxide is crystalline,nanocrystalline, or amorphous. In some embodiments, the tungsten oxideis substantially nanocrystalline, with grain sizes, on average, fromabout 5 nm to 50 nm (or from about 5 nm to 20 nm), as characterized bytransmission electron microscopy (TEM). The tungsten oxide morphologymay also be characterized as nanocrystalline using x-ray diffraction(XRD). For example, nanocrystalline electrochromic tungsten oxide may becharacterized by the following XRD features: a crystal size of about 10to 100 nm (e.g., about 55 nm. Further, nanocrystalline tungsten oxidemay exhibit limited long range order, e.g., on the order of several(about 5 to 20) tungsten oxide unit cells.

The thickness of the electrochromic layer 106 depends on thecathodically coloring material selected for the electrochromic layer. Insome embodiments, the electrochromic layer 106 is about 50 nm to 2,000nm, or about 200 nm to 700 nm. In some embodiments, the electrochromiclayer is about 300 nm to about 500 nm. The thickness of theelectrochromic layer 106 is also substantially uniform. In oneembodiment, a substantially uniform electrochromic layer varies onlyabout ±10% in each of the aforementioned thickness ranges. In anotherembodiment, a substantially uniform electrochromic layer varies onlyabout ±5% in each of the aforementioned thickness ranges. In anotherembodiment, a substantially uniform electrochromic layer varies onlyabout ±3% in each of the aforementioned thickness ranges.

Generally, in cathodically coloring electrochromic materials, thecolorization/tinting (or change in any optical property—e.g.,absorbance, reflectance, and transmittance) of the electrochromicmaterial is caused by reversible ion insertion into the material (e.g.,intercalation) and a corresponding injection of a charge balancingelectron. Typically some fraction of the ion responsible for the opticaltransition is irreversibly bound up in the electrochromic material. Asexplained below, some or all of the irreversibly bound ions are used tocompensate “blind charge” in the material. In most electrochromicmaterials, suitable ions include lithium ions (Li⁺) and hydrogen ions(H⁺) (i.e., protons). In some cases, however, other ions will besuitable. These include, for example, deuterium ions (D⁺), sodium ions(Na⁺), potassium ions (K⁺), calcium ions (Ca⁺⁺), barium ions (Ba⁺⁺),strontium ions (Sr⁺⁺), and magnesium ions (Mg⁺⁺). In various embodimentsdescribed herein, lithium ions are used to produce the electrochromicphenomena. Intercalation of lithium ions into tungsten oxide (WO_(3−y)(0<y≤˜0.3)) causes the tungsten oxide to change from transparent (clearstate) to blue (tinted state).

Referring again to FIG. 1A, in electrochromic stack 120, ion conductinglayer 108 overlays electrochromic layer 106. On top of ion conductinglayer 108 is anodically coloring layer 110 (also referred to as counterelectrode layer 110). In certain embodiments, this ion conducting layer108 is omitted, and the cathodically coloring electrochromic layer 106is in direct physical contact with the anodically coloring counterelectrode layer 110. In some embodiments, counter electrode layer 110 isinorganic and/or solid. The counter electrode layer may comprise one ormore of a number of different materials that are capable of serving asreservoirs of ions when the electrochromic device is in the clear state.In this respect the anodically coloring counter electrode layer istermed an “ion storage layer” in some contexts. During an electrochromictransition initiated by, e.g., application of an appropriate electricpotential, the anodically coloring counter electrode layer transferssome or all of the ions it holds to the cathodically coloringelectrochromic layer, changing the electrochromic layer to the tintedstate. Concurrently, in the case of NiWNbO, the counter electrode layertints with the loss of ions.

In various embodiments, the anodically coloring counter electrodematerial includes nickel, tungsten, niobium, and oxygen. The materialsmay be provided together as NiWNbO, at any appropriate composition. TheNiWNbO material is especially beneficial as an anodically coloringmaterial because it is particularly clear or color neutral in the clearstate. Many counter electrode materials are slightly tinted (colored)even in their clear states. For instance, NiO is brown and NiWOgenerally has a slight yellow tint in the clear state. For aestheticreasons, it is preferable that both the cathodically coloring andanodically coloring materials in an electrochromic device are very clear(transparent) and colorless when the device is in the clear state.

Further, some counter electrode materials exhibit good color qualities(i.e., are very clear in their clear state), but are unsuitable forcommercial use because the materials' ability to undergo rapid opticaltransitions fades over time. In other words, for these materials theduration of an optical transition increases with the age/use of thedevice. In this case, a newly fabricated window would exhibit higherswitching speeds than an identical window that has been in use for e.g.,six months. One example of an anodically coloring counter electrodematerial that shows good color quality but decreasing transition speedover time is nickel tantalum oxide (NiTaO). By contrast, NiWNbO is avaluable candidate for the anodically coloring counter electrodematerial because it exhibits good color qualities and maintains goodswitching speeds over long periods of use.

The NiWNbO may have various compositions when used as an anodicallycoloring material. In certain embodiments, particular balances may bemade between the various components of the NiWNbO. For instance, anatomic ratio of Ni:(W+Nb) in the material may fall between about 1.5:1and 3:1, for example between about 1.5:1 and 2.5:1, or between about 2:1and 2.5:1. In a particular example the atomic ratio of Ni:(W+Nb) isbetween about 2:1 and 3:1. The atomic ratio of Ni:(W+Nb) relates to theratio of (i) nickel atoms in the material to (ii) the sum of the numberof tungsten and niobium atoms in the material.

The NiWNbO material may also have a particular atomic ratio of W:Nb. Incertain embodiments, the atomic ratio of W:Nb is between about 0.1:1 and6:1, for example between about 0.2:1 and 5:1, or between about 1:1 and3:1, or between about 1.5:1 and 2.5:1, or between about 1.5:1 and 2:1.In some cases the atomic ratio of W:Nb is between about 0.2:1 and 1:1,or between about 1:1 and 2:1, or between about 2:1 and 3:1, or betweenabout 3:1 and 4:1, or between about 4:1 and 5:1. In someimplementations, particular atomic ratios of Ni:(W+Nb) and W:Nb areused. All combinations of disclosed Ni:(W+Nb) compositions and disclosedW:Nb compositions are contemplated, though only certain combinations areexplicitly listed herein. For instance, the atomic ratio of Ni:(W+Nb)may be between about 1.5:1 and 3:1, where the atomic ratio of W:Nb isbetween about 1.5:1 and 3:1. In another example, the atomic ratio ofNi:(W+Nb) may be between about 1.5:1 and 2.5:1, where the atomic ratioof W:Nb is between about 1.5:1 and 2.5:1. In a further example, theatomic ratio of Ni:(W+Nb) may be between about 2:1 and 2.5:1, where theatomic ratio of W:Nb is between about 1.5:1 and 2:1, or between about0.2:1 and 1:1, or between about 1:1 and 2:1, or between about 4:1 and5:1.

Other example materials for the counter electrode include, but are notlimited to, nickel oxide, nickel tungsten oxide, nickel vanadium oxide,nickel chromium oxide, nickel aluminum oxide, nickel manganese oxide,nickel magnesium oxide, chromium oxide, iron oxide, cobalt oxide,rhodium oxide, iridium oxide, manganese oxide, Prussian blue. Thematerials (e.g., metal and oxygen) may be provided at differentstoichiometric ratios as appropriate for a given application. Opticallypassive counter electrodes may be used in some cases. In certainembodiments, the counter electrode material may comprise cerium titaniumoxide, cerium zirconium oxide, nickel oxide, nickel-tungsten oxide,vanadium oxide, and mixtures of oxides (e.g., a mixture of NiO and/orNi₂O₃ with WO₃). Doped formulations of these oxides may also be used,with dopants including, e.g., tantalum, niobium, tungsten, etc.

Because anodically coloring counter electrode layer 110 contains theions used to produce the electrochromic phenomenon in the cathodicallycoloring electrochromic material when the cathodically coloringelectrochromic material is in the clear state, the anodically coloringcounter electrode preferably has high transmittance and a neutral colorwhen it holds significant quantities of these ions.

When charge is removed from an anodically coloring counter electrode110, e.g., made of conventional nickel tungsten oxide (i.e., ions aretransported from the counter electrode 110 to the electrochromic layer106), the counter electrode layer will turn from a (more or less)transparent state to a brown tinted state. Similarly, when charge isremoved from an anodically coloring counter electrode 110 made ofNiWNbO, the counter electrode layer will turn from a transparent stateto a brown tinted state. However, the transparent state of a NiWNbOcounter electrode layer may be clearer, having less color (particularlyless yellow color, for example) than the transparent state of a NiWOcounter electrode layer.

The counter electrode morphology may be crystalline, amorphous, or somemixture thereof. Crystalline phases may be nanocrystalline. In someembodiments, the nickel-tungsten-niobium-oxide (NiWNbO) counterelectrode material is amorphous or substantially amorphous. Varioussubstantially amorphous counter electrodes have been found to performbetter, under some conditions, in comparison to their crystallinecounterparts. The amorphous state of the counter electrode oxidematerial may be obtained through the use of certain processingconditions, described below. While not wishing to be bound to any theoryor mechanism, it is believed that amorphous nickel-tungsten oxide ornickel-tungsten-niobium oxide is produced by relatively low energy atomsin the sputtering process. Low energy atoms are obtained, for example,in a sputtering process with lower target powers, higher chamberpressures (i.e., lower vacuum), and/or larger source to substratedistances. Amorphous films are also more likely to form where there is arelatively higher fraction/concentration of heavy atoms (e.g., W). Underthe described process conditions films with better stability underUV/heat exposure are produced. Substantially amorphous materials mayhave some crystalline, typically but not necessarily nanocrystalline,material dispersed in the amorphous matrix. The grain size and amountsof such crystalline materials are described in more detail below.

In some embodiments, the counter electrode morphology may includemicrocrystalline, nanocrystalline and/or amorphous phases. For example,the counter electrode may be, e.g., a material with an amorphous matrixhaving nanocrystals distributed throughout. In certain embodiments, thenanocrystals constitute about 50% or less of the counter electrodematerial, about 40% or less of the counter electrode material, about 30%or less of the counter electrode material, about 20% or less of thecounter electrode material or about 10% or less of the counter electrodematerial (by weight or by volume depending on the embodiment). Incertain embodiments, the nanocrystals have a maximum diameter of lessthan about 50 nm, in some cases less than about 25 nm, less than about10 nm, or less than about 5 nm. In some cases, the nanocrystals have amean diameter of about 50 nm or less, or about 10 nm or less, or about 5nm or less (e.g., about 1-10 nm).

In certain embodiments, it is desirable to have a nanocrystal sizedistribution where at least about 50% of the nanocrystals have adiameter within 1 standard deviation of the mean nanocrystal diameter,for example where at least about 75% of the nanocrystals have a diameterwithin 1 standard deviation of the mean nanocrystal diameter or where atleast about 90% of the nanocrystals have a diameter within 1 standarddeviation of the mean nanocrystal diameter.

It has been found that counter electrodes that include an amorphousmatrix tend to operate more efficiently compared to counter electrodesthat are relatively more crystalline. In certain embodiments, theadditive may form a host matrix in which domains of the base anodicallycoloring material may be found. In various cases, the host matrix issubstantially amorphous. In certain embodiments, the only crystallinestructures in the counter electrode are formed from a base anodicallycoloring electrochromic material in, e.g., oxide form. One example of abase anodically coloring electrochromic material in oxide form is nickeltungsten oxide. Additives may contribute to forming an amorphous hostmatrix that is not substantially crystalline, but which incorporatesdomains (e.g., nanocrystals in some cases) of the base anodicallycoloring electrochromic material. One example additive is niobium. Inother embodiments, the additive and the anodically coloring basematerial together form a chemical compound with covalent and/or ionicbonding. The compound may be crystalline, amorphous, or a combinationthereof. In other embodiments, the anodically coloring base materialforms a host matrix in which domains of the additive exist as discretephases or pockets. For example certain embodiments include an amorphouscounter electrode having an amorphous matrix of a first material, with asecond material, also amorphous, distributed throughout the firstmaterial in pockets, for example, pockets of the diameters describedherein for crystalline materials distributed throughout an amorphousmatrix.

In some embodiments, the thickness of the counter electrode is about 50nm about 650 nm. In some embodiments, the thickness of the counterelectrode is about 100 nm to about 400 nm, sometimes in the range ofabout 150 nm to 300 nm, or between about 200 nm to 300 nm. The thicknessof the counter electrode layer 110 is also substantially uniform. In oneembodiment, a substantially uniform counter electrode layer varies onlyabout ±10% in each of the aforementioned thickness ranges. In anotherembodiment, a substantially uniform counter electrode layer varies onlyabout ±5% in each of the aforementioned thickness ranges. In anotherembodiment, a substantially uniform counter electrode layer varies onlyabout ±3% in each of the aforementioned thickness ranges.

The amount of ions held in the counter electrode layer during the clearstate (and correspondingly in the electrochromic layer during the tintedstate) and available to drive the electrochromic transition depends onthe composition of the layers as well as the thickness of the layers andthe fabrication method. Both the electrochromic layer and the counterelectrode layer are capable of supporting available charge (in the formof lithium ions and electrons) in the neighborhood of several tens ofmillicoulombs per square centimeter of layer surface area. The chargecapacity of an electrochromic film is the amount of charge that can beloaded and unloaded reversibly per unit area and unit thickness of thefilm by applying an external voltage or potential. In one embodiment,the WO₃ layer has a charge capacity of between about 30 and about 150mC/cm²/micron. In another embodiment, the WO₃ layer has a chargecapacity of between about 50 and about 100 mC/cm²/micron. In oneembodiment, the NiWNbO layer has a charge capacity of between about 75and about 200 mC/cm²/micron. In another embodiment, the NiWNbO layer hasa charge capacity of between about 100 and about 150 mC/cm²/micron.

Returning to FIG. 1A, in between electrochromic layer 106 and counterelectrode layer 110, there is often an ion conducting layer 108. Ionconducting layer 108 serves as a medium through which ions aretransported (in the manner of an electrolyte) when the electrochromicdevice transforms between the clear state and the tinted state.Preferably, ion conducting layer 108 is highly conductive to therelevant ions for the electrochromic and the counter electrode layers,but has sufficiently low electron conductivity that negligible electrontransfer takes place during normal operation. A thin ion conductinglayer (also sometimes referred to as an ion conductor layer) with highionic conductivity permits fast ion conduction and hence fast switchingfor high performance electrochromic devices. In certain embodiments, theion conducting layer 108 is inorganic and/or solid. When fabricated froma material and in a manner that produces relatively few defects, the ionconductor layer can be made very thin to produce a high performancedevice. In various implementations, the ion conductor material has anionic conductivity of between about 10⁸ Siemens/cm or ohm⁻¹ cm⁻¹ andabout 10⁹ Siemens/cm or ohm⁻¹ cm⁻¹ and an electronic resistance of about10¹¹ ohms-cm.

In other embodiments, the ion conductor layer may be omitted. In suchembodiments, no separate ion conductor material is deposited whenforming an electrochromic stack for an electrochromic device. Instead,in these embodiments the cathodically coloring electrochromic materialmay be deposited in direct physical contact with the anodically coloringcounter electrode material. One or both of the anodically coloring andcathodically coloring materials may be deposited to include a portionthat is oxygen rich compared to the remaining portion of the material.Typically, the oxygen rich portion is in contact with the other type oflayer. For instance, an electrochromic stack may include an anodicallycoloring material in contact with a cathodically coloring material,where the cathodically coloring material includes an oxygen-rich portionin direct physical contact with the anodically coloring material. Inanother example, an electrochromic stack includes an anodically coloringmaterial in contact with a cathodically coloring material, where theanodically coloring material includes an oxygen-rich portion in directphysical contact with the cathodically coloring material. In a furtherexample, both the anodically coloring material and the cathodicallycoloring material include an oxygen-rich portion, where the oxygen-richportion of the cathodically coloring material is in direct physicalcontact with the oxygen-rich portion of the anodically coloringmaterial. The oxygen-rich portions of these layers may be provided asdistinct sub-layers (e.g., a cathodically or anodically coloringmaterial includes an oxygen-rich sublayer and a less-oxygen-richsublayer). The oxygen-rich portion of the layers may also be provided ina graded layer (e.g., the cathodically or anodically coloring materialmay include a gradient in oxygen concentration, the gradient being in adirection normal to the surface of the layers. Embodiments where the ionconductor layer is omitted and the anodically coloring counter electrodematerial is in direct contact with the cathodically coloringelectrochromic material are further discussed in the following U.S.Patents, each of which is herein incorporated by reference in itsentirety: U.S. Pat. Nos. 8,300,298, and 8,764,950.

Returning to the embodiment of FIG. 1A, examples of suitable materialsfor the lithium ion conductor layer include lithium silicate, lithiumaluminum silicate, lithium oxide, lithium tungstate, lithium aluminumborate, lithium borate, lithium zirconium silicate, lithium niobate,lithium borosilicate, lithium phosphosilicate, lithium nitride, lithiumoxynitride, lithium aluminum fluoride, lithium phosphorus oxynitride(LiPON), lithium lanthanum titanate (LLT), lithium tantalum oxide,lithium zirconium oxide, lithium silicon carbon oxynitride (LiSiCON),lithium titanium phosphate, lithium germanium vanadium oxide, lithiumzinc germanium oxide, and other ceramic materials that allow lithiumions to pass through them while having a high electrical resistance(blocking electron movement therethrough). Any material, however, may beused for the ion conducting layer 108 provided it can be fabricated withlow defectivity and it allows for the passage of ions between thecounter electrode layer 110 to the electrochromic layer 106 whilesubstantially preventing the passage of electrons.

In certain embodiments, the ion conducting layer is crystalline,amorphous, or a mixture thereof. Typically, the ion conducting layer isamorphous. In another embodiment, the ion conducting layer isnanocrystalline. In another embodiment, the ion conducting layer is amixed amorphous and crystalline phase, where the crystalline phase isnanocrystalline.

The thickness of the ion conducting layer 108 may vary depending on thematerial. In some embodiments, the ion conducting layer 108 is about 5nm to 100 nm thick, preferably about 10 nm to 60 nm thick. In someembodiments, the ion conducting layer is about 15 nm to 40 nm thick orabout 25 nm to 30 nm thick. The thickness of the ion conducting layer isalso substantially uniform.

Ions transported across the ion conducting layer between theelectrochromic layer and the counter electrode layer serve to effect acolor change in the electrochromic layer (i.e., change theelectrochromic device from the clear state to the tinted state) whenthey reside in the electrochromic layer. For devices having anodicallycoloring counter electrode layers, the absence of these ions inducescolor in the counter electrode layer. Depending on the choice ofmaterials for the electrochromic device stack, such ions include lithiumions (Li⁺) and hydrogen ions (H⁺) (i.e., protons). As mentioned above,other ions may be employed in certain embodiments. These includedeuterium ions (D⁺), sodium ions (Na⁺), potassium ions (K⁺), calciumions (Ca⁺⁺), barium ions (Ba⁺⁺), strontium ions (Sr⁺⁺), and magnesiumions (Mg⁺⁺). In certain embodiments, hydrogen ions are not used becauseside reactions during operation of the device cause recombination tohydrogen gas which may escape the device and degrade performance. Thus,ions that do not have this issue, for example lithium ions, may be used.

The electrochromic devices in embodiments herein are also scalable tosubstrates smaller or larger than architectural glass. An electrochromicstack can be deposited onto substrates that are a wide range of sizes,up to about 12 inches by 12 inches, or even 80 inches by 120 inches.

In some embodiments, electrochromic glass is integrated into aninsulating glass unit (IGU). An insulating glass unit consists ofmultiple glass panes assembled into a unit, generally with the intentionof maximizing the thermal insulating properties of a gas contained inthe space formed by the unit while at the same time providing clearvision through the unit. Insulating glass units incorporatingelectrochromic glass would be similar to insulating glass unitscurrently known in the art, except for electrical leads for connectingthe electrochromic glass to voltage source. Due to the highertemperatures (due to absorption of radiant energy by an electrochromicglass) that electrochromic insulating glass units may experience, morerobust sealants than those used in conventional insulating glass unitsmay be necessary. For example, stainless steel spacer bars, hightemperature polyisobutylene (PIB), new secondary sealants, foil coatedPIB tape for spacer bar seams, and the like.

Heterogeneous Counter Electrode

As shown in FIG. 1A, the anodically coloring counter electrode may be asingle homogeneous layer in some cases. However, in a number ofembodiments herein, the anodically coloring counter electrode layer isheterogeneous in composition or a physical feature such as morphology.Such heterogeneous counter electrode layers may exhibit improved color,switching behavior, lifetime, uniformity, process window, etc.Heterogeneous counter electrodes are further discussed in U.S.Provisional Patent Application No. 62/192,443, which is hereinincorporated by reference in its entirety.

In certain embodiments, the counter electrode layer includes two or moresublayers, where the sublayers have different compositions and/ormorphologies. One or more of such sublayers may also have a gradedcomposition. The composition and/or morphology gradient may have anyform of transition including a linear transition, a sigmoidaltransition, a Gaussian transition, etc. A number of advantages can berealized by providing the counter electrode as two or more sublayers.For instance, the sublayers may be different materials that havecomplimentary properties. One material may promote better color qualitywhile another material promotes high quality, long lifetime switchingbehavior. The combination of materials may promote a high degree of filmquality and uniformity while at the same time achieving a high rate ofdeposition (and therefore throughput). Some of the approaches outlinedherein may also promote better control of the lithium distributionthroughout the electrochromic device, and in some cases may lead toimprovements in morphology in the counter electrode (e.g., highertransmission) and the overall reduction of defects in the electrochromicdevice. Another benefit that may result from various embodiments hereinis the availability of one or more intermediate states. Differences inelectrical potentials between various sublayers may allow for lithium toreside in discrete locations (e.g., within particular sublayers toparticular degrees), thereby enabling the electrochromic device toachieve intermediate tint states between e.g., a fully tinted device anda fully clear device. In some cases, intermediate states can be achievedby applying different voltages to the device. The inclusion of multiplesub-layers within the counter electrode layer may reduce or eliminatethe need to apply different voltages to achieve different intermediatetint states. These and other benefits of the disclosed embodiments arefurther described below.

In some cases, a counter electrode includes a first sublayer of a firstanodically coloring counter electrode material and one or moreadditional sublayers of a second anodically coloring counter electrodematerial. In various cases, the first sublayer of the CE layer may besituated closer to the cathodically coloring electrochromic materialthan the second (and optional additional) sublayer(s) of the CE layer.In some implementations, the first sublayer is a flash layer, which isgenerally characterized as a thin and often quickly deposited layertypically having a thickness of not greater than about 50 nm. The flashlayer, if present, may or may not exhibit electrochromic properties. Incertain embodiments, the flash layer is made of a counter electrodematerial that does not change color with remainingelectrochromic/counter electrode layers (though this layer may have acomposition that is very similar to other layers such as an anodicallycoloring layer). In some embodiments, the first sublayer/flash layer hasa relatively high electronic resistivity, for example between about 1and 5×10¹⁰ Ohm-cm.

Generally speaking, the first and second anodically coloring counterelectrode materials may each, independently, be any anodically coloringcounter electrode material. The first and/or second counter electrodematerials may be binary metal oxides (e.g., oxides that include twometals in addition to lithium or other transported ion, NiWO being oneexample), ternary metal oxides (e.g., oxides that include three metals,NiWNbO being one example), or even more complex materials. In many casesthe materials also include lithium, which to a certain extent may bemobile within the device.

In a particular example, the first anodically coloring material is NiWO.In these or other examples, the second anodically coloring material maybe NiWO that is doped with or otherwise includes an additional metal(e.g., a non-alkali metal, a transition metal, a post-transition metal,or a metalloid in certain cases), with one example material beingNiWNbO.

In some embodiments, the first and second anodically coloring materialscontain the same elements, but in different proportions. For example,both materials may contain Ni, W, and Nb, but two or three of theelements may be present in different mass or atomic ratios. In someother embodiments, the first and second sublayers may be moresignificantly different from one another compositionally. For instance,the first and second sublayers (and any additional sublayers) may eachbe any anodically coloring material, regardless of the composition ofthe other sublayers.

The two or more sublayers may have different physical properties. Invarious cases, a material used in one or more of the sublayers is amaterial that would not perform well (e.g., would exhibit poor colorquality, poor lifetime performance, slow switching speed, slowdeposition rate, etc.) as a counter electrode material if providedwithout the accompanying sublayer(s).

FIG. 1B provides a cross sectional view of an electrochromic stack, asdeposited, according to one embodiment. The stack includes transparentconductive oxide layers 204 and 214. In contact with transparentconductive oxide layer 204 is a cathodically coloring electrochromiclayer 206. In contact with transparent conductive oxide layer 214 isanodically coloring counter electrode layer 210, which includes twosublayers 210 a and 210 b. The first sublayer 210 a of the counterelectrode is in contact with the electrochromic layer 206, and thesecond sublayer 210 b is in contact with the transparent conductiveoxide layer 214. In this embodiment, no separate ion conductor layer isdeposited (though an interfacial region serving as an ion conductorlayer may be formed in situ from this construct as described in U.S.patent application Ser. No. 13/462,725, filed May 2, 2012, and titled“ELECTROCHROMIC DEVICES,” which is herein incorporated by reference inits entirety).

The first and second sublayers 210 a and 210 b of the anodicallycoloring counter electrode layer 210 may have different compositionsand/or morphologies. In various examples, the second sublayer 210 bincludes at least one metal and/or metal oxide that is not present inthe first sublayer 210 a. In a particular example, the first sublayer210 a is NiWO and the second sublayer 210 b is NiWO doped or otherwisecombined with another metal (e.g., NiWTaO, NiWSnO, NiWNbO, NiWZrO,etc.). In another embodiment, the first and second sublayers 210 a and210 b include the same elements at different relative concentrations.

In some embodiments, the first sublayer 210 a is a flash layer. Flashlayers are typically thin layers (and as such they are typically, butnot necessarily, deposited relatively quickly). In some embodiments, afirst sublayer of an anodically coloring counter electrode is a flashlayer that is between about 10-100 nm thick, for example between about20-50 nm thick. In a number of embodiments, the first sublayer/flashlayer may be a material that deposits at a higher deposition rate thanthe material of the remaining sublayers. Similarly, the flash layer maybe deposited at a lower power than the remaining sublayers. Theremaining sublayer(s) may be thicker than the first sublayer 210 a inmany embodiments. In certain embodiments where the counter electrodelayer 210 includes two sublayers such as 210 a and 210 b, the secondsublayer 210 b may be between about 20-300 nm thick, for example betweenabout 150-250 nm thick.

In certain embodiments, the second sublayer 210 b is homogeneous withrespect to composition. FIG. 1D presents a graph showing theconcentration of various elements present in the first and secondsublayers 210 a and 210 b of FIG. 1B in a particular embodiment wherethe first sublayer is NiM2O and the second sublayer is compositionallyhomogeneous NiM1M2O. The first sublayer 210 a is labeled CE1 and thesecond sublayer 210 b is labeled CE2. In this example, the firstsublayer has a composition that is about 25% nickel, about 8% M1, andabout 66% oxygen, and the second sublayer has a composition that isabout 21% nickel, about 3% M1, about 68% oxygen, and about 8% M2. M2 maybe a metal in various embodiments.

In other embodiments, the second sublayer 210 b may include a gradedcomposition. The composition may be graded with respect to the relativeconcentration of a metal therein. For instance, in some cases the secondsublayer 210 b has a graded composition with respect to a metal that isnot present in the first sublayer. In one particular example, the firstsublayer is NiWO and the second sublayer is NiWNbO, where theconcentration of niobium is graded throughout the second sublayer. Therelative concentrations of the remaining elements (excluding theniobium) may be uniform throughout the second sublayer, or they may alsochange throughout this sublayer. In a particular example, theconcentration of oxygen may also be graded within the second sublayer210 b (and/or within the first sublayer 210 a).

FIG. 1E presents a graph showing the concentration of M2 present in thefirst and second sublayers 210 a and 210 b of FIG. 1B in a particularembodiment where the first sublayer is NiM1O and the second sublayer isa graded layer of NiM1M2O. As with FIG. 1D, the first sublayer 210 a islabeled CE1 and the second sublayer is labeled CE2. In this example, theconcentration of M2 rises throughout the second sublayer, to a value ofabout 15% (atomic). The other elements are omitted from the figure;though in one embodiment, they reflect the compositions substantially asdescribed in relation to FIG. 1D, adjusted as appropriate to accommodatethe changing M2 concentration.

In certain embodiments, the first and second sublayers may havecompositions that are more different from one another. FIG. 1F presentsa graph showing the concentration of various elements present in thefirst and second sublayers 210 a and 210 b of FIG. 1B in an embodimentwhere the first sublayer is NiM1O and the second sublayer is NiM2O. In aparticular case, M1 is tungsten and M2 is vanadium, though other metalsand materials may also be used. While FIG. 4C shows the concentration ofoxygen and nickel remaining constant throughout both sublayers of thecounter electrode layer, this is not always the case. The particularcompositions described with respect to FIGS. 1D-1F are merely providedas examples and are not intended to be limiting. Different materials andconcentrations/compositions may also be used.

FIG. 1C shows an additional example of an electrochromic stack similarto that shown in FIG. 1B. The stack in FIG. 1C includes transparentconductive oxide layers 304 and 314, cathodically coloringelectrochromic layer 306, and anodically coloring counter electrodelayer 311. Here, counter electrode layer 311 is made of three sublayers311 a-c. The first sublayer 311 a may be a flash layer as describedabove with respect to the first sublayer 210 a of FIG. 1B. Each of thesublayers 311 a-c may have a different composition. The second and thirdsublayers 311 b and 311 c may include the same elements at differentrelative concentrations in some embodiments. In another embodiment, allof the sublayers 311 a-c include the same elements at different relativeconcentrations.

In some embodiments, additional sublayers may be provided. Theadditional sublayers may be homogeneous with respect to composition, orthey may be graded as described above. The trends described withrelation to the first, second, and third sublayers of FIGS. 1B and 1Cmay also hold true in throughout additional sublayers in variousembodiments where such additional sublayers are provided. In oneexample, the counter electrode is deposited to include four sublayers,where the first sublayer (positioned closest to the electrochromiclayer) includes a first material (e.g., NiM1O) and the second, third,and fourth sublayers include a second material (e.g., NiM1M2O) thatincludes an additional element (e.g., a metal) that is not present inthe first sublayer. The concentration of this additional element may behigher in sublayers that are farther away from the electrochromic layerand lower in sublayers that are closer to the electrochromic layer. Asone particular example, the first sublayer (closest to theelectrochromic layer) is NiWO, the second sublayer is NiWNbO with 3%(atomic) Nb, the third sublayer is NiWNbO with 7% (atomic) Nb, and thefourth sublayer (farthest from the electrochromic layer) is NiWNbO with10% (atomic) Nb.

In still another embodiment, the counter electrode may be provided as asingle layer, but the composition of the counter electrode layer may begraded. The composition may be graded with respect to one or moreelements present in the material. In some embodiments, the counterelectrode has a graded composition with respect to one or more metals inthe material. In these or other embodiments, the counter electrode mayhave a graded composition with respect to one or more non-metals, forexample oxygen. FIG. 1G presents a graph showing the concentration of M2present in a counter electrode layer where the counter electrode isprovided as a single layer with a graded composition. In this example,the composition is graded with respect to a metal therein (M2). Theother elements (Ni, M1, O) are omitted from FIG. 1G. In one embodiment,these elements reflect the compositions substantially as described inrelation to FIG. 1D or 1F, adjusted as appropriate to accommodate thechanging M2 composition.

Without wishing to be bound by theory or mechanism of action, it isbelieved that the disclosed first sublayer may help protect the ionconducting layer and/or electrochromic layer from damage arising fromexcessive heating or other harsh condition during deposition of thecounter electrode layer. The first sublayer may be deposited underconditions that are milder than those used to deposit the remainingsublayers. For instance, in some embodiments, the first sublayer may bedeposited at a sputter power between about 5-20 kW/m², and the secondsublayer may be deposited at a sputter power between about 20-45 kW/m².In one particular example where the first sublayer is NiWO and thesecond sublayer is NiWNbO, the NiWNbO may be deposited using highersputtering power than the NiWO. This high power process, if performed todeposit directly on the ion conducting and/or electrochromic layer,might in some implementations degrade the ion conducting and/orelectrochromic layer, for example due to excessive heating and prematurecrystallization of the relevant materials, and/or due to loss of oxygenin the ion conducting and/or electrochromic layer. However, where a thinflash layer of NiWO is provided as a first sublayer, this NiWO layer canbe deposited under more gentle conditions. The NiWO sublayer may thenprotect the underlying ion conducting and/or electrochromic layer duringdeposition of subsequent NiWNbO sublayer(s). This protection may lead toa more reliable, better functioning electrochromic device.

The disclosed embodiments may also exhibit improved performance arisingfrom higher quality morphology and improved morphology control withinthe anodically coloring materials. For example, by providing the counterelectrode as two or more sublayers, one or more additional interfacesare introduced within the counter electrode (e.g., interfaces where thesublayers contact one another). These interfaces can disrupt theformation of crystals, for example due to renucleation and related graingrowth effects. Such effects may act to prevent the crystals fromgrowing larger and limit the size of any crystals that form. This effecton morphology may lead to fabrication of devices with fewer voids orother defects.

Without wishing to be bound by theory or mechanism of action, it is alsobelieved that the disclosed methods may be used to achieve improvedcontrol over the distribution of lithium within an electrochromicdevice. Different counter electrode materials exhibit differentaffinities for lithium, and therefore the choice of counter electrodematerial(s) affects how the lithium ions are distributed in anelectrochromic device. By selecting particular materials andcombinations of materials, the distribution of lithium within the devicecan be controlled. In certain embodiments, the sublayers of the counterelectrode include materials having different affinities for lithium. Forinstance, the material of the first sublayer may have a higher or loweraffinity for lithium compared to the material of the second (oradditional) sublayer(s) of the counter electrode.

Relatedly, the disclosed methods may be used to achieve improved controlover the total amount of lithium used to fabricate an electrochromicdevice. In various cases, lithium may be added during deposition of thecounter electrode layer. In some embodiments, lithium may be addedduring deposition of one or more sublayers of the counter electrode. Inthese or other embodiments, lithium may be added between depositions ofsubsequent sublayers of the counter electrode. By controlling thedistribution of lithium and the total amount of lithium within theelectrochromic device, device uniformity and appearance may be improved.

Another benefit that may arise with the disclosed techniques is improvedcolor and switching performance. As mentioned above, certain counterelectrode materials exhibit better performance in terms of color (e.g.,clearer clear states, more attractive tinted states, etc.), switchingspeed, lifetime, and other properties. However, certain materials thatpromote high quality results with respect to one property may havedrawbacks with respect to other properties. For instance, a materialthat is desirable because it exhibits a very transparent and uncoloredclear state may suffer problems related to slow switching speed and/orshort lifetime. By combining this material with another counterelectrode material (which may have its own problems such as a relativelymore yellow clear state), it is possible in various implementations toachieve a counter electrode with improved properties. The drawbacksrelated to one counter electrode material may be mitigated by propertiesof another counter electrode material.

Method of Fabricating Electrochromic Windows

Deposition of the Electrochromic Stack

As mentioned above, one aspect of the embodiments is a method offabricating an electrochromic window. In a broad sense, the methodincludes sequentially depositing on a substrate (i) a cathodicallycoloring electrochromic layer, (ii) an optional ion conducting layer,and (iii) an anodically coloring counter electrode layer to form a stackin which the ion conducting layer separates the cathodically coloringelectrochromic layer and the anodically coloring counter electrodelayer. The sequential deposition employs a single integrated depositionsystem having a controlled ambient environment in which the pressure,temperature, and/or gas composition are controlled independently of anexternal environment outside of the integrated deposition system, andthe substrate does not leave the integrated deposition system at anytime during the sequential deposition of the electrochromic layer, theion conducting layer, and the counter electrode layer. (Examples ofintegrated deposition systems which maintain controlled ambientenvironments are described in more detail below in relation to FIGS.5A-E.) The gas composition may be characterized by the partial pressuresof the various components in the controlled ambient environment. Thecontrolled ambient environment also may be characterized in terms of thenumber of particles or particle densities. In certain embodiments, thecontrolled ambient environment contains fewer than 350 particles (ofsize 0.1 micrometers or larger) per m³. In certain embodiments, thecontrolled ambient environment meets the requirements of a class 1000clean room (US FED STD 209E), or a class 100 clean room (US FED STD209E). In certain embodiments, the controlled ambient environment meetsthe requirements of a class 10 clean room (US FED STD 209E). Thesubstrate may enter and/or leave the controlled ambient environment in aclean room meeting class 1000, class 100 or even class 10 requirements.

Typically, but not necessarily, this method of fabrication is integratedinto a multistep process for making an electrochromic window usingarchitectural glass as the substrate. For convenience, the followingdescription contemplates the method and its various embodiments in thecontext of a multistep process for fabricating an electrochromic window,but methods are not so limited. Electrochromic mirrors and other devicesmay be fabricated using some or all of the operations and approachesdescribed herein.

FIG. 2 is a cross-sectional representation of an electrochromic windowdevice, 600, in accord with a multistep process such as that describedin relation to FIG. 4A. FIG. 4A depicts a process flow describing amethod, 700, of fabricating an electrochromic window which incorporateselectrochromic device 600. FIG. 3 is a top view of device 600 showingthe location of trenches cut into the device. Thus, FIGS. 2, 3, and 4Awill be described together. One aspect of the description is anelectrochromic window including device 600 and another aspect of thedescription is a method, 700, of fabricating an electrochromic windowwhich includes device 600. Included in the following description aredescriptions of FIGS. 4B-4E. FIGS. 4B-4D depict specific methods offabricating an electrochromic stack which is part of device 600. FIG. 4Edepicts a process flow for a conditioning process used in fabricating,e.g., device 600.

FIG. 2 shows a specific example of an electrochromic device, 600, whichis fabricated starting with a substrate made of glass 605 whichoptionally has a diffusion barrier 610 coating and a first transparentconducting oxide (TCO) coating 615 on the diffusion barrier. Method 700employs a substrate that is, for example, float glass with sodiumdiffusion barrier and antireflective layers followed by a transparentconductive layer, for example a transparent conductive oxide 615. Asmentioned above, substrates suitable for devices include glasses soldunder the trademarks TEC Glass® by Pilkington of Toledo, Ohio, andSUNGATE® 300 and SUNGATE® 500 by PPG Industries, of Pittsburgh, Pa. Thefirst TCO layer 615 is the first of two conductive layers used to formthe electrodes of electrochromic device 600 fabricated on the substrate.

Method 700 begins with a cleaning process, 705, where the substrate iscleaned to prepare it for subsequent processing. As mentioned above, itis important to remove contaminants from the substrate because they cancause defects in the device fabricated on the substrate. One criticaldefect is a particle or other contaminant that creates a conductivepathway across the IC layer and thus shorts the device locally causingvisually discernable anomalies in the electrochromic window. One exampleof a cleaning process and apparatus suitable for the fabrication methodsherein is Lisec™ (a trade name for a glass washing apparatus and processavailable from (LISEC Maschinenbau Gmbh of Seitenstetten, Austria).

Cleaning the substrate may include mechanical scrubbing as well assonication conditioning to remove unwanted particulates. As mentioned,particulates may lead to cosmetic flaws as well as local shorting withinthe device.

Once the substrate is cleaned, a first laser scribe process, 710, isperformed in order to remove a line of the first TCO layer on thesubstrate. In one embodiment, the resulting trench ablates through boththe TCO and the diffusion barrier (although in some cases the diffusionbarrier is not substantially penetrated). FIG. 2 depicts this firstlaser scribe trench, 620. A trench is scribed in the substrate acrossthe entire length of one side of the substrate in order to isolate anarea of the TCO, near one edge of the substrate, which will ultimatelymake contact with a first bus bar, 640, used to provide current to asecond TCO layer, 630, which is deposited on top of electrochromic (EC)stack 625 (which includes the electrochromic, ion conducting and counterelectrode layers as described above). FIG. 3 shows schematically (not toscale) the location of trench 620. In the depicted embodiment, thenon-isolated (main) portion of the first TCO layer, on the diffusionbarrier, ultimately makes contact with a second bus bar, 645. Isolationtrench 620 may be needed because, in certain embodiments, the method ofattaching the first bus bar to the device includes pressing it throughthe device stack layers after they are laid down (both on the isolatedportion of the first TCO layer and the main portion of the first TCOlayer). Those of skill in the art will recognize that other arrangementsare possible for providing current to the electrodes, in this case TCOlayers, in the electrochromic device. The TCO area isolated by the firstlaser scribe is typically an area along one edge of the substrate thatwill ultimately, along with the bus bars, be hidden when incorporatedinto the integrated glass unit (IGU) and/or window pane, frame orcurtain wall. The laser or lasers used for the first laser scribe aretypically, but not necessarily, pulse-type lasers, for examplediode-pumped solid state lasers. For example, the laser scribes can beperformed using a suitable laser from IPG Photonics (of Oxford Mass.),or from Ekspla (of Vilnius Lithuania).

The laser trench is dug along a side of the substrate from end to end toisolate a portion of the first TCO layer; the depth and width dimensionsof trench 620 made via first laser scribe 710 should be sufficient toisolate the first TCO layer from the bulk TCO once the device issubsequently deposited. The depth and width of the trench should besufficient to prevent any remaining particulates to short across thetrench. In one embodiment, the trench is between about 300 nm and 900 nmdeep (e.g., between about 300 nm and 500 nm) and between about 20 μm and50 μm wide. In another embodiment, the trench is between about 350 nmand 450 nm deep and between about 30 μm and 45 μm wide. In anotherembodiment, the trench is about 400 nm deep and about 40 μm wide.

After the first laser scribe 710, the substrate is cleaned again(operation 715), typically but not necessarily, using cleaning methodsdescribed above. This second cleaning process is performed to remove anydebris caused by the first laser scribe. Once cleaning operation 715 iscomplete, the substrate is ready for deposition of EC stack 625. This isdepicted in process flow 700 as process 720. As mentioned above, themethod includes sequentially depositing on a substrate (i) acathodically coloring EC layer, (ii) an optional IC layer, and (iii) ananodically coloring CE layer (e.g., NiWNbO in various embodiments) toform a stack in which the IC layer separates the EC layer and the CElayer using a single integrated deposition system having a controlledambient environment in which the pressure and/or gas composition arecontrolled independently of an external environment outside of theintegrated deposition system, and the substrate does not leave theintegrated deposition system at any time during the sequentialdeposition of the EC layer, the IC layer, and the CE layer. In oneembodiment, each of the sequentially deposited layers is physical vapordeposited. In general the layers of the electrochromic device may bedeposited by various techniques including physical vapor deposition,chemical vapor deposition, plasma enhanced chemical vapor deposition,and atomic layer deposition, to name a few. The term physical vapordeposition as used herein includes the full range of art understood PVDtechniques including sputtering, evaporation, ablation, and the like.FIG. 4B depicts one embodiment of process 720. First the cathodicallycoloring EC layer is deposited on the substrate, process 722, then theIC layer is deposited, process 724 (as noted above, in certainembodiments the IC layer, and therefore process 724, are omitted), thenthe anodically coloring CE layer, process 726. The reverse order ofdeposition is also an embodiment, that is, where the CE layer isdeposited first, then the optional IC layer and then the EC layer. Inone embodiment, each of the electrochromic layer, the optional ionconducting layer, and the counter electrode layer is a solid phaselayer. In another embodiment, each of the electrochromic layer, theoptional ion conducting layer, and the counter electrode layer includesonly inorganic material.

It should be understood that while certain embodiments are described interms of a counter electrode layer, an ion conductor layer, and anelectrochromic layer, any one or more of these layers may be composed ofone or more sub-layers, which may have distinct compositions, sizes,morphologies, charge densities, optical properties, etc. Further any oneor more of the device layers may have a graded composition or a gradedmorphology in which the composition or morphology, respectively, changesover at least a portion of the thickness of the layer. In one example,the concentration of oxygen, a dopant, or charge carrier varies within agiven layer, at least as the layer is fabricated. In another example,the morphology of a layer varies from crystalline to amorphous. Suchgraded composition or morphology may be chosen to impact the functionalproperties of the device. In some cases, additional layers may be addedto the stack. In one example a heat spreader layer is interposed betweenone or both TCO layers and the EC stack.

Also, as described above, the electrochromic devices of certainembodiments utilize ion movement between the electrochromic layer andthe counter electrode layer via an ion conducting layer. In someembodiments these ions (or neutral precursors thereof) are introduced tothe stack as one or more layers (as described below in more detail inrelation to FIGS. 4C and 4D) that eventually intercalate into the stack.In some embodiments these ions are introduced into the stackconcurrently with one or more of the electrochromic layer, the ionconducting layer, and the counter electrode layer. In one embodiment,where lithium ions are used, lithium is, e.g., sputtered along with thematerial used to make the one or more of the stack layers or sputteredas part of a material that includes lithium (e.g., by a method employinglithium nickel tungsten niobium oxide). In one embodiment, the IC layeris deposited via sputtering a lithium silicon aluminum oxide target. Inanother embodiment, the Li is cosputtered along with silicon aluminum inorder to achieve the desired film.

Referring again to process 722 in FIG. 4B, in one embodiment, depositingthe electrochromic layer comprises depositing WO_(x), e.g. where x isless than 3.0 and at least about 2.7. In this embodiment, the WO_(x) hasa substantially nanocrystalline morphology. In some embodiments, theelectrochromic layer is deposited to a thickness of between about 200 nmand 700 nm. In one embodiment, depositing the electrochromic layerincludes sputtering tungsten from a tungsten containing target.Particular deposition conditions for forming a WO_(x) electrochromiclayer are further discussed in U.S. patent application Ser. No.12/645,111, which is herein incorporated by reference in its entirety.

It should be understood that while deposition of the EC layer isdescribed in terms of sputtering from a target, other depositiontechniques are employed in some embodiments. For example, chemical vapordeposition, atomic layer deposition, and the like may be employed. Eachof these techniques, along with PVD, has its own form of material sourceas is known to those of skill in the art.

Referring again to FIG. 4B, operation 724, once the EC layer isdeposited, the IC layer is deposited. In one embodiment, depositing theion conducting layer includes depositing a material selected from thegroup consisting of a tungsten oxide, a tantalum oxide, a niobium oxide,and a silicon aluminum oxide. Particular deposition conditions forforming an IC layer are further discussed in U.S. patent applicationSer. No. 12/645,111, which is incorporated by reference above. Incertain embodiments, depositing the ion conducting layer includesdepositing the ion conducting layer to a thickness of between about 10and 100 nm. As noted elsewhere herein, the IC layer may be omitted incertain embodiments.

Referring again to FIG. 4B, operation 726, after the IC layer isdeposited, the anodically coloring CE layer is deposited. In oneembodiment, depositing the counter electrode layer includes depositing alayer of nickel-tungsten-niobium-oxide (NiWNbO). In a specificembodiment, depositing the counter electrode layer includes sputtering atarget including about 30% (by weight) to about 70% of tungsten innickel and/or niobium in an oxygen containing environment to produce alayer of nickel tungsten niobium oxide (the niobium being provided by atungsten/nickel/niobiumtarget at an appropriate composition, or byanother target, or through another source such as an evaporated niobiumsource). In another embodiment the target is between about 40% and about60% tungsten in nickel (and/or niobium), in another embodiment betweenabout 45% and about 55% tungsten in nickel (and/or niobium), and in yetanother embodiment about 51% tungsten in nickel (and/or niobium).

In certain embodiments where the anodically coloring counter electrodelayer includes NiWNbO, many deposition targets or combinations oftargets may be used. For instance, individual metal targets of nickel,tungsten, and niobium can be used. In other cases at least one of thetargets includes an alloy. For instance, an alloy target ofnickel-tungsten can be used together with a metal niobium target. Inanother case, an alloy target of nickel-niobium can be used togetherwith a metal tungsten target. In a further case, an alloy oftungsten-niobium can be used together with a metal nickel target. In yeta further case, an alloy target containing a nickel-tungsten-niobiummaterial may be used. Moreover, any of the listed targets can beprovided as an oxide. Oftentimes, sputtering occurs in the presence ofoxygen, and such oxygen is incorporated into the material. Sputtertargets containing oxygen may be used alternatively or in addition to anoxygen-containing sputtering atmosphere.

The sputtering target(s) for forming the anodically coloring counterelectrode material may have compositions that permit the counterelectrode to be formed at any of the compositions described herein. Inone example where a single sputter target is used, the sputter targetmay have a composition that matches the composition of any of the NiWNbOmaterials disclosed herein. In other examples a combination of sputtertargets are used, and the composition of the combined targets allows fordeposition at any of the NiWNbO materials disclosed herein. Further, thesputter targets may be arranged in any way that permits the material tobe deposited as desired, as discussed further below.

In one embodiment, the gas composition used when forming the CE containsbetween about 30% and about 100% oxygen, in another embodiment betweenabout 80% and about 100% oxygen, in yet another embodiment between about95% and about 100% oxygen, in another embodiment about 100% oxygen. Inone embodiment, the power density used to sputter the CE target isbetween about 2 Watts/cm² and about 50 Watts/cm² (determined based onthe power applied divided by the surface area of the target); in anotherembodiment between about 5 Watts/cm² and about 20 Watts/cm²; and in yetanother embodiment between about 8 Watts/cm² and about 10 Watts/cm², inanother embodiment about 8 Watts/cm². In some embodiments, the powerdelivered to effect sputtering is provided via direct current (DC). Inother embodiments, pulsed DC/AC reactive sputtering is used. In oneembodiment, where pulsed DC/AC reactive sputtering is used, thefrequency is between about 20 kHz and about 400 kHz, in anotherembodiment between about 20 kHz and about 50 kHz, in yet anotherembodiment between about 40 kHz and about 50 kHz, in another embodimentabout 40 kHz.

The pressure in the deposition station or chamber, in one embodiment, isbetween about 1 and about 50 mTorr, in another embodiment between about20 and about 40 mTorr, in another embodiment between about 25 and about35 mTorr, in another embodiment about 30 mTorr. In some cases, a nickeltungsten oxide NiWO ceramic target is sputtered with, e.g., argon andoxygen. In one embodiment, the NiWO is between about 15% (atomic) Ni andabout 60% Ni; between about 10% W and about 40% W; and between about 30%O and about 75% O. In another embodiment, the NiWO is between about 30%(atomic) Ni and about 45% Ni; between about 10% W and about 25% W; andbetween about 35% O and about 50% O. In one embodiment, the NiWO isabout 42% (atomic) Ni, about 14% W, and about 44% O. In anotherembodiment, depositing the counter electrode layer includes depositingthe counter electrode layer to a thickness of between about 150 and 350nm; in yet another embodiment between about 200 and about 250 nm thick.The above conditions may be used in any combination with one another toeffect deposition of a high quality NiWNbO layer.

The sputtering process for forming the CE layer may utilize one or moresputter targets. In one example where one sputter target is used, thetarget may include nickel, tungsten, and niobium. In some cases thesputter target also includes oxygen. The sputter target may include agrid or other overlapping shape where different portions of the gridinclude the different relevant materials (e.g., certain portions of thegrid may include elemental nickel, elemental tungsten, elementalniobium, a nickel-tungsten alloy, a nickel-niobium alloy, and/or atungsten-niobium alloy). In some cases, a sputter target may be an alloyof the relevant materials (e.g., two or more of nickel, tungsten, andniobium). Where two or more sputter targets are used, each sputtertarget may include at least one of the relevant materials (e.g.,elemental and/or alloy forms of nickel, tungsten, and/or niobium, any ofwhich can be provided in oxide form). The sputter targets may overlap insome cases. The sputter targets may also rotate in some embodiments. Asnoted, the counter electrode layer is typically an oxide material.Oxygen may be provided as a part of the sputter target and/or sputtergas. In certain cases, the sputter targets are substantially puremetals, and sputtering is done in the presence of oxygen to form theoxide.

In one embodiment, in order to normalize the rate of deposition of theCE layer, multiple targets are used so as to obviate the need forinappropriately high power (or other inappropriate adjustment to desiredprocess conditions) to increase deposition rate. In one embodiment, thedistance between the CE target (cathode or source) to the substratesurface is between about 35 mm and about 150 mm; in another embodimentbetween about 45 mm and about 130 mm; and in another embodiment betweenabout 70 mm and about 100 mm.

As noted, one or more rotating targets may be used in some cases. Invarious cases, a rotating target may include an interior magnet. FIG. 6Apresents a view of a rotating target 900. Inside the rotating target 900is a magnet 902, which (when the target is supplied with appropriatepower) causes material to sputter off of the target surface 904 in asputter cone 906 (sputter cones are also sometimes referred to assputter plasmas). The magnet 902 may extend along the length of thesputter target 900. In various embodiments, the magnet 902 may beoriented to extend radially outward such that the resulting sputter cone906 emanates from the sputter target 900 in a direction normal to thetarget's surface 904 (the direction being measured along a central axisof the sputter cone 906, which typically corresponds to the averagedirection of the sputter cone 906). The sputter cone 906 may be v-shapedwhen viewed from above, and may extend along the height of the target900 (or the height of the magnet 902 if not the same as the height ofthe target 900). The magnet 902 inside the rotating target 900 may befixed (i.e., though the surface 904 of the target 900 rotates, themagnet 902 within the target 900 does not rotate) such that the sputtercone 906 is also fixed. The small circles/dots depicted in the sputtercone 906 represent sputtered material that emanates from the sputtertarget 900. Rotating targets may be combined with other rotating targetsand/or planar targets as desired.

In one example, two rotating targets are used to deposit a NiWNbOanodically coloring EC layer: a first target including nickel andtungsten, and a second target including niobium (either or bothoptionally in oxide form). FIG. 6B presents a top down view of adeposition system for depositing an anodically coloring layer in thismanner. The nickel tungsten target 910 and the niobium target 912 eachinclude an interior magnet 914. The magnets 914 are angled toward oneanother such that the sputter cones 916 and 918 from the nickel tungstentarget 910 and niobium target 912, respectively, overlap. FIG. 6B alsoshows a substrate 920 passing in front of the targets 910 and 912. Asshown, the sputter cones 916 and 918 closely overlap where they impactthe substrate 920. In some embodiments, the sputter cones from varioussputter targets may closely overlap with one another (e.g., thenon-overlapping area over which only a single sputter cone reaches whendepositing on a substrate is less than about 10%, for example less thanabout 5% of the total area over which either sputter cone reaches). Inother embodiments, the sputter cones may diverge from one another to agreater degree such that either or both of the sputter cones has anon-overlapping area that is at least about 10%, for example at leastabout 20%, or at least about 30%, or at least about 50%, of the totalarea over which either sputter cone reaches.

In a similar embodiment to the one shown in FIG. 6B, one sputter targetis tungsten and the other is an alloy of nickel and niobium (either orboth targets optionally being in oxide form). Similarly, one sputtertarget may be nickel and the other may be an alloy of tungsten andniobium (either or both target optionally being in oxide form). In arelated embodiment, three sputter targets are used: a niobium target, anickel target, and a tungsten target (any of which can optionally be inoxide form). The sputter cones from each of the three targets mayoverlap by angling the magnets as appropriate. Also, shielding, gratingsand/or other additional plasma shaping elements may be used to aid increating the appropriate plasma mixture to form the NiWNbO.

Various sputter target designs, orientations, and implementations arefurther discussed in U.S. patent application Ser. No. 13/462,725, filedMay 2, 2012, and titled “ELECTROCHROMIC DEVICES,” which is hereinincorporated by reference in its entirety.

The density and orientation/shape of material that sputters off of asputter target depends on various factors including, for example, themagnetic field shape and strength, pressure, and power density used togenerate the sputter plasma. The distance between adjacent targets, aswell as the distance between each target and substrate, can also affecthow the sputter plasmas will mix and how the resulting material isdeposited on the substrate.

In certain embodiments, two different types of sputter targets areprovided to deposit a single layer in an electrochromic stack: (a)primary sputter targets, which sputter material onto a substrate, and(b) secondary sputter targets, which sputter material onto the primarysputter targets. The primary and secondary sputter targets may includeany combination of metal, metal alloys, and metal oxides that achieve adesired composition in a deposited layer. In one particular example, aprimary sputter target includes an alloy of nickel and tungsten, and asecondary sputter target includes niobium. In another example a primarysputter target includes niobium and a secondary sputter target includesan alloy of nickel and tungsten. These sputter targets may be usedtogether to deposit an anodically coloring layer of NiWNbO. Othercombinations of alloys (e.g., nickel-niobium, tungsten-niobium) andmetals (e.g., nickel, tungsten) can also be used. Any sputter target maybe provided as an oxide.

A number of different setups are possible when using both primary andsecondary sputter targets. FIGS. 7A and 7B presents top-down views ofone embodiment of a deposition station for depositing a NiWNbOanodically coloring counter electrode layer. Though presented in thespecific context of depositing NiWNbO, the sputter target configurationsdiscussed herein may be used to deposit any material in theelectrochromic stack, provided that the targets are of appropriatecompositions to deposit the desired material in the stack. A primarysputter target 1001 and a secondary sputter target 1002 are provided,each with an internal magnet 1003. Each sputter target in this exampleis a rotating sputter target, though planar or other shaped targets maybe used as well. The targets may rotate in the same direction or inopposite directions. The secondary sputter target 1002 sputters materialonto the primary sputter target 1001 when no substrate 1004 is presentbetween the two targets, as shown in FIG. 7A. This deposits materialfrom the secondary sputter target 1002 onto the primary sputter target1001. Then, as the substrate 1004 moves into position between the twotargets, sputtering from the secondary sputter target 1002 ceases andsputtering from the primary sputter target 1001 onto the substrate 1004begins, as shown in FIG. 7B.

When material is sputtered off of the primary sputter target 1001 anddeposited onto the substrate 1004, the deposited material includesmaterial that originated from both the primary and secondary sputtertargets 1001 and 1002, respectively. In effect, this method involvesin-situ formation of an intermixed sputter target surface on the primarysputter target 1001. One advantage of this method is that a freshcoating of material from the secondary sputter target 1002 (e.g., insome cases this material is niobium, tungsten, nickel, or combinationsand/or alloys thereof) is periodically deposited on the surface of theprimary sputter target 1001. The intermixed materials are then deliveredtogether to the substrate 1004.

In a related embodiment shown in FIG. 7C, a secondary sputter target1022 is positioned behind a primary sputter target 1021, and a substrate1024 passes in front of the primary sputter target 1021 such that itdoes not block the line of sight between the two targets 1021 and 1022.Each of the sputter targets may include a magnet 1023. In thisembodiment, there is no need to periodically stop sputtering from thesecondary sputter target 1021 onto the primary sputter target 1022.Instead, such sputtering can occur continuously. Where the primarysputter target 1021 is located in between the substrate 1024 and thesecondary sputter target 1022 (e.g., there is no line of sight betweenthe secondary sputter target 1022 and the substrate 1024), the primarysputter target 1021 should rotate such that material that is depositedonto the primary sputter target 1021 can be sputtered onto the substrate1024. There is more flexibility in the design of the secondary sputtertarget 1022. In a related embodiment, the secondary sputter target maybe a planar or other non-rotating target. Where two rotating targets areused, the targets may rotate in the same direction or in oppositedirections.

In similar embodiments, the secondary sputter target (e.g., thesecondary target in FIGS. 7A-7C) may be replaced with another secondarymaterial source. The secondary material source may provide material tothe primary sputter target through means other than sputtering. In oneexample, the secondary material source provides evaporated material tothe primary sputter target. The evaporated material may be any componentof a layer being deposited. In various examples the evaporated materialis an elemental metal or metal oxide. Particular examples of evaporatedmaterial include niobium, tungsten, and nickel, which may be used toform a NiWNbO anodically coloring counter electrode material. In oneembodiment, elemental niobium is evaporated onto a primary sputtertarget including a mixture and/or alloy of nickel and tungsten. Where asecondary material source provides evaporated material, the secondarymaterial source may be provided at any location relative to the primarysputter target and substrate. In some embodiments the secondary materialsource is provided such that it is behind and deposits primarily on theprimary sputter target, much like the setup shown in FIG. 7C.

Where both a primary and a secondary sputter target are used, thesecondary sputter target may be operated at a potential that is cathodiccompared to the potential of the primary sputter target (which isalready cathodic). Alternatively, the targets may be operatedindependently. Still further, regardless of relative target potentials,neutral species ejected from the secondary target will deposit on theprimary target. Neutral atoms will be part of the flux, and they willdeposit on a cathodic primary target regardless of relative potentials.

In various embodiments, reactive sputtering may be used to deposit oneor more materials in the electrochromic stack. FIG. 8 is a diagramshowing the sputtering deposition rate from a sputter target as afunction of oxygen concentration at a fixed power. As shown in FIG. 8,there is a strong hysteresis effect related to the oxygen concentrationprofile the target has been exposed to/operated under. For instance,when starting from a low oxygen concentration and increasing to a higheroxygen concentration, the deposition rate stays fairly high until theoxygen concentration reaches a point at which the sputter target formsan oxide that cannot be removed from the target sufficiently quickly. Atthis point the deposition rate drops down, and the sputter targetessentially forms a metal oxide target. The deposition rate for an oxidetarget is generally much lower than the deposition rate for a metaltarget, all other conditions being equal. The relatively high depositionrate region in FIG. 8 corresponds to a metal deposition regime, whilethe relatively low deposition rate region corresponds to a metal oxidedeposition regime. When the target is initially exposed to/operatedunder a high oxygen concentration then exposed to/operated under arelatively lower concentration, the deposition rate stays fairly lowuntil the oxygen concentration reaches a point at which the depositionrate jumps up to a higher level. As shown in FIG. 8, the oxygenconcentration at which these changes take place is different dependingon whether the oxygen concentration is increasing or decreasing. Theexact oxygen concentrations at which the regime changes occur can becontrolled by changing the target power density and magnetic strength ofthe internal magnet 1003. For example, if one target is sputtering asubstantially higher flux of metal atoms from the surface (due to higherpower and/or magnetic strength), that target would likely stay in themetal deposition regime, compared to a target which is sputtering a verylow flux of metal atoms. Such hysteresis effects can be used toadvantage in a deposition process.

In certain embodiments where two or more sputter targets are used todeposit a material in the electrochromic stack, one target may beoperated in the metal deposition regime and another target may beoperated in the metal oxide deposition regime. By controlling the targetpower density, magnetic strength of the internal magnet 1003, and theatmosphere to which each target is exposed/operated under over time, itis possible to operate at both of these regimes simultaneously. In oneexample, a first nickel tungsten target is exposed to a relatively lowconcentration of oxygen and then brought to a mid-level concentration ofoxygen such that it operates in the metal deposition regime. A secondniobium target is exposed to a relatively high concentration of oxygenand then brought to a mid-level concentration of oxygen such that itoperates in the metal oxide deposition regime. The two targets can thenbe brought together, still exposed to the mid-level oxygenconcentration, where they are used to deposit material onto a substrateunder both regimes (the first target continuing to operate under themetal deposition regime and the second target continuing to operateunder the metal oxide deposition regime).

The different atmosphere exposures for each target may not be needed inmany cases. Other factors besides different historical oxygen exposurecan result in the targets operating under the different depositionregimes. For instance, the targets may have different hysteresis curvesdue to the different material in the targets. As such, the targets maybe able to operate under different regimes even if they are historicallyexposed to and operated under the same atmospheric oxygen conditions.Further, the amount of power applied to each target can significantlyaffect the deposition regime experienced by each target. In one example,therefore, one target is operated under a metal deposition regime andanother target is operated under a metal oxide deposition regime due tothe different powers applied to each target. This approach may be easierbecause it does not require separating the targets from one another suchthat they can be exposed to different oxygen concentrations. Oneadvantage to operating the targets at different points in the hysteresiscurves is that the composition of a deposited material can be closelycontrolled.

It should be understood that while the order of deposition operations isdepicted in FIG. 4B (and implied in FIG. 2) to be first EC layer, secondIC layer, and finally CE layer, the order can be reversed in variousembodiments. In other words, when as described herein “sequential”deposition of the stack layers is recited, it is intended to cover thefollowing “reverse” sequence, first CE layer, second IC layer, and thirdEC layer, as well the “forward” sequence described above. Both theforward and reverse sequences can function as reliable high-qualityelectrochromic devices. Further, it should be understood that conditionsrecited for depositing the various EC, IC, and CE materials recitedhere, are not limited to depositing such materials. Other materials may,in some cases, be deposited under the same or similar conditions.Moreover, the IC layer may be omitted in certain cases. Further,non-sputtering deposition conditions may be employed in some embodimentsto create the same or similar deposited materials as those described inthe context of FIG. 6 and FIG. 7.

Since the amount of charge each of the EC and the CE layers can safelyhold varies, depending on the material used, the relative thickness ofeach of the layers may be controlled to match capacity as appropriate.In one embodiment, the electrochromic layer includes tungsten oxide andthe counter electrode includes nickel tungsten niobium oxide, and theratio of thicknesses of the electrochromic layer to the counterelectrode layer is between about 1.7:1 and 2.3:1, or between about 1.9:1and 2.1:1 (with about 2:1 being a specific example).

Referring again to FIG. 4B, operation 720, after the CE layer isdeposited, the EC stack is complete. It should be noted that in FIG. 4A,process operation 720, which refers to “depositing stack” means in thiscontext, the EC stack plus the second TCO layer (sometimes referred toas the “ITO” when indium tin oxide is used to make the second TCO).Generally “stack” in this description refers to the EC-IC-CE layers;that is, the “EC stack.” Referring again to FIG. 4B, in one embodiment,represented by process 728, a TCO layer is deposited on the stack.Referring to FIG. 2, this would correspond to second TCO layer 630 on ECstack 625. Process flow 720 is finished once process 728 is complete.Typically, but not necessarily, a capping layer is deposited on the ECstack. In some embodiments, the capping layer is SiAlO, similar to theIC layer. Particular deposition conditions for forming a second TCOlayer are further discussed in U.S. patent application Ser. No.12/645,111, which is incorporated by reference above.

As mentioned, the EC stack is fabricated in an integrated depositionsystem where the substrate does not leave the integrated depositionsystem at any time during fabrication of the stack. In one embodiment,the second TCO layer is also formed using the integrated depositionsystem where the substrate does not leave the integrated depositionsystem during deposition of the EC stack and the TCO layer. In oneembodiment, all of the layers are deposited in the integrated depositionsystem where the substrate does not leave the integrated depositionsystem during deposition; that is, in one embodiment the substrate is aglass sheet and a stack including the EC layer, the IC layer and the CElayer, sandwiched between a first and a second TCO layer, is fabricatedon the glass where the glass does not leave the integrated depositionsystem during deposition. In another implementation of this embodiment,the substrate is glass with a diffusion barrier deposited prior to entryin the integrated deposition system. In another implementation thesubstrate is glass and the diffusion barrier, a stack including the EClayer, the IC layer and the CE layer, sandwiched between a first and asecond TCO layer, are all deposited on the glass where the glass doesnot leave the integrated deposition system during deposition.

While not wishing to be bound by theory, it is believed that prior artelectrochromic devices suffered from high defectivity for variousreasons, one of which is the integration of unacceptably high numbers ofparticles into the IC layer during fabrication. Care was not taken toensure that each of the EC layer, IC layer, and CE layer were depositedin a single integrated deposition apparatus under a controlled ambientenvironment. In one process, the IC layer is deposited by a sol gelprocess, which is necessarily performed apart from other vacuumintegrated processes. In such process, even if the EC layer and/or theCE layer are deposited in a controlled ambient environment, therebypromoting high quality layers, the substrate would have to be removedfrom the controlled ambient environment to deposit the IC layer. Thiswould normally involve passing the substrate through a load lock (fromvacuum or other controlled ambient environment to an externalenvironment) prior to formation of the IC layer. Passage through a loadlock typically introduces numerous particles onto the substrate.Introducing such particles immediately before the IC layer is depositedgreatly increases the likelihood that defects will form in the criticalIC layer. Such defects lead to bright spots or constellations asdiscussed above.

As mentioned above, lithium may be provided with the EC, CE and/or IClayers as they are formed on the substrate. This may involve, forexample, co-sputtering of lithium together with the other materials of agiven layer (e.g., tungsten and oxygen). In certain embodimentsdescribed below the lithium is delivered via a separate process andallowed to diffuse or otherwise incorporate into the EC, CE and/or IClayers. In some embodiments, only a single layer in the electrochromicstack is lithiated. For example, only the anodically coloring CE layeris lithiated in some examples. In other cases, only the cathodicallycoloring EC layer is lithiated. In still other cases, only the IC layeris lithiated.

In some embodiments, the electrochromic stack includes a counterelectrode layer in direct physical contact with an electrochromic layer,without an ion conducting layer in between. The electrochromic and/orcounter electrode layer may include an oxygen-rich portion in contactwith the other of these layers. The oxygen-rich portion includes theelectrochromic material or counter electrode material, with a higherconcentration of oxygen than in the remaining portion of theelectrochromic layer and/or counter electrode layer. Electrochromicdevices fabricated according to such a design are further discussed anddescribed in U.S. Pat. No. 8,300,298, filed Apr. 30, 2010, which isincorporated by reference above.

In certain embodiments, fabrication of the electrochromic stack occursin an integrated deposition system. Such an integrated system may allowfor deposition of the various layers in the stack without breakingvacuum. In other cases, one or more layers in the stack may be depositedby a process that requires removal from a protected vacuum environment.For example, in some cases one or more layers (e.g., a cathodicallycoloring EC layer) is deposited on a substrate under vacuum usingphysical vapor deposition, then the substrate is removed from vacuum andan ion conductor layer is deposited using a sol-gel (or othernon-vacuum) process, and then the substrate is returned to a vacuumenvironment for deposition of the anodically coloring counter electrodelayer. Sol-gel processes involve producing solid materials from smallmolecules. Monomers are converted into a colloidal solution that acts asthe precursor for an integrated network of discrete particles or networkpolymers. Examples of ion conductor materials that may be depositedinclude, for example, silicate-based structures, lithium silicate,lithium aluminum silicate, lithium aluminum borate, lithium borate,lithium Zirconium silicate, lithium niobate, lithium borosilicate,lithium phosphosilicate, lithium nitride, lithium aluminum fluoride, andother such lithium-based ceramic materials, silicas, or silicon oxides,silicon dioxide, and tantalum oxide.

Direct Lithiation of the Electrochromic Stack

In some embodiments, as mentioned above, intercalation of lithium ionsis responsible for switching the optical state of an electrochromicdevice stack. It should be understood that the needed lithium may beintroduced to the stack by various means. For example, lithium may beprovided to one or more of these layers concurrently with the depositionof the material of the layer (e.g., concurrent deposition of lithium andtungsten oxide during formation of the EC layer). In some cases,however, the process of FIG. 4B may be punctuated with one or moreoperations for delivering lithium to the EC layer, the IC layer, and/orthe CE layer. For example, lithium may also be introduced via one ormore separate lithiation steps in which elemental lithium is deliveredwithout substantial deposition of other material. Such lithiationstep(s) may take place after deposition of the EC layer, the IC layer,and/or the CE layer. Alternatively (or in addition), one or morelithiation steps may take intermediate between steps performed todeposit a single layer. For example, a counter electrode layer may bedeposited by first depositing a limited amount of nickel tungstenniobium oxide, followed by directly depositing lithium, and thenconcluded by depositing additional amounts of nickel tungsten niobiumoxide. Such approaches may have certain advantages such as betterseparating the lithium from the ITO (or other material of a conductivelayer) which improves adhesion and prevents undesirable side reactions.One example of a stack formation process employing a separate lithiationoperation is presented in FIG. 4C. In certain cases, the lithiationoperation(s) takes place while the deposition of a given layer istemporarily halted to allow lithium to be introduced before depositionof the layer is completed.

FIG. 4C depicts a process flow, 720 a, for depositing the stack onto asubstrate in a manner analogous to process 720 of FIG. 4A. Process flow720 a includes depositing an EC layer, operation 722, depositing an IClayer, operation 724, and depositing a CE layer, operation 726, asdescribed in relation to FIG. 4B. However, process flow 720 a differsfrom 720 by the addition of lithiation operations 723 and 727. In oneembodiment, the lithium is physical vapor deposited using an integrateddeposition system where the substrate does not leave the integrateddeposition system at any time during the sequential deposition of theelectrochromic layer, the ion conducting layer, the counter electrodelayer, and the lithium. Particular conditions for lithiation are furtherdiscussed in U.S. patent application Ser. No. 12/645,111, which isincorporated by reference above.

In one embodiment of the dual lithiation method, as explained above, theEC layer is treated with sufficient lithium to satisfy the requirementsof the EC material irreversibly bound lithium (to, e.g., compensate“blind charge”). The lithium needed for reversible cycling is added tothe CE layer (which also may have a blind charge). In certainembodiments, the lithium needed to compensate the blind charge can betitrated by monitoring optical density of the EC layer as lithium isadded since the EC layer will not substantially change color untilsufficient lithium has been added to fully compensate the blind charge.

One of ordinary skill in the art would appreciate that because metalliclithium is pyrophoric, i.e., highly reactive with moisture and oxygen,that lithiation methods described herein where lithium might be exposedto oxygen or moisture are performed either under vacuum, inertatmosphere or both. The controlled ambient environment of apparatus andmethods of the disclosed embodiments provides flexibility in lithiumdepositions, particularly where there are multiple lithiation steps. Forexample, where lithiation is performed in a titration process and/oramong multiple steps in a stack layering, the lithium can be protectedfrom exposure to oxygen or moisture.

In certain embodiments, the lithiation is performed at a rate sufficientto prevent formation of a substantial thickness of free lithium on theEC layer surface. In one embodiment, during lithiation of the EC layer,lithium targets are spaced sufficiently to give time for lithium todiffuse into the EC layer. Optionally, the substrate (and hence the EClayer) is heated to between about 100° C. and about 150° C. to enhancediffusion of lithium into the EC layer. Heating may be done separatelyor in combination with target spacing and substrate translation past thetarget(s). In some cases, the substrate is moved back and forth in frontof a sputtered lithium target in order to slow the delivery of lithiumto the substrate and prevent accumulation of free metallic lithium onthe stack surface. Isolation protocols may be used for performinglithiation. Such protocols are further discussed in U.S. patentapplication Ser. No. 12/645,111, which is incorporated by referenceabove.

FIG. 4D depicts another process flow, 720 b, for depositing the stackonto a substrate. The process is analogous to process flow 700 of FIG.4A. Process flow 720 b includes depositing an EC layer (operation 722)depositing an IC layer (operation 724) and depositing a CE layer(operation 726) as described in relation to FIG. 4B. However, processflow 720 b differs from 720 because there is an intervening lithiationoperation 727. In this embodiment of the process of stack deposition,all the required lithium is added by delivering lithium to the CE layerand allowing the lithium to intercalate into the EC layer via diffusionthrough the IC layer during and/or after stack fabrication.

Multistep Thermochemical Conditioning

Referring again to FIG. 4A, once the stack is deposited, the device issubjected to a multistep thermo-chemical conditioning (MTC) process (seeblock 730). Typically, the MTC process is performed only after alllayers of the electrochromic stack have been formed. Some embodiments ofthe MTC process 730 are depicted in more detail in FIG. 4E. Note thatthe MTC process can be conducted entirely ex situ, i.e., outside of theintegrated deposition system used to deposit the stack, or at leastpartially or wholly in situ, i.e., inside the deposition system withoute.g. breaking vacuum or otherwise moving the substrate outside thecontrolled ambient environment used to fabricate the stack. In certainembodiments, the initial portions of the MTC process are performed insitu, and later portions of the process are performed ex situ. Incertain embodiments, portions of the MTC are performed prior todeposition of certain layers, for example, prior to deposition of thesecond TCO layer.

Referring to FIG. 4E, and in accordance with certain embodiments, thedevice is first thermally treated under non-reactive conditions (e.g.,under an inert gas). See block 732. Next, the device is subjected to athermal treatment under reactive conditions. See block 734. Particularconditions for performing the thermal treatments are further discussedin U.S. patent application Ser. No. 12/645,111, which is incorporated byreference above.

As mentioned above, additional layers may be needed for improved opticalperformance (e.g. anti-reflectives), durability (due to physicalhandling), hermeticity, and the like. Addition of one or more of theselayers is meant to be included in additional embodiments to thosedescribed above.

The lithiation and high temperature processing operations describedherein can affect the composition and structure of various materials inthe electrochromic stack. As one example, where an electrochromic stackincludes a cathodically coloring EC layer in direct contact with ananodically coloring CE layer (with no separate ion conducting layerdeposited in between them), the thermal processing operations can changethe composition and/or structure of the cathodically coloring EC andanodically coloring CE layers at an interfacial region between theselayers, to thereby form a region that has ion conducting, electronicallyinsulating properties. Similarly, lithiation and thermal processingoperations can affect the composition and structure of an anodicallycoloring counter electrode layer. In various cases an anodicallycoloring counter electrode layer is improved through such operations.

Fabrication Process for Completion of the Device

Again referring to FIG. 4A, a second laser scribe (block 740) isperformed. Laser scribe 740 is performed across the length of thesubstrate near the outer edge of the stack, on the two sides of thesubstrate perpendicular to the first laser scribe. FIG. 3 shows thelocation of the trenches, 626, formed by laser scribe 740. This scribeis also performed all the way through the first TCO (and diffusionbarrier if present) to the substrate in order to further isolate theisolated portion of the first TCO layer (where the first bus bar will beconnected) and to isolate the stack coating at the edges (e.g. near amask) to minimize short circuits due to deposition roll off of the stacklayers. In one embodiment, the trench is between about 100 μm and 300 μmwide. In another embodiment, the trench is between about 150 μm and 250μm wide. In another embodiment, the trench is about 150 μm wide. Thetrench should be deep enough to effectively isolate the relevantcomponents.

Next, a third laser scribe, 745, is performed along the perimeter of thestack near the edge of the substrate opposite the first laser scribe andparallel to the first laser scribe. This third laser scribe is only deepenough to isolate the second TCO layer and the EC stack, but not cutthrough the first TCO layer. Referring to FIG. 2, laser scribe 745 formsa trench, 635, which isolates the uniform conformal portions EC stackand second TCO from the outermost edge portions which can suffer fromroll off (e.g. as depicted in FIG. 2, the portion of layers 625 and 630near area 650 isolated by cutting trench 635) and thus cause shortsbetween the first and second TCO layers in region 650 near where thesecond bus bar will be attached. Trench 635 also isolates roll offregions of the second TCO from the second bus bar. Trench 635 is alsodepicted in FIG. 3. One of ordinary skill in the art would appreciatethat laser scribes 2 and 3, although scribed at different depths, couldbe done in a single process whereby the laser cutting depth is variedduring a continuous path around the three sides of the substrate asdescribed. First at a depth sufficient to cut past the first TCO (andoptionally the diffusion barrier) along a first side perpendicular tothe first laser scribe, then at a depth sufficient only to cut throughto the bottom of the EC stack along the side opposite and parallel tothe first laser scribe, and then again at the first depth along thethird side, perpendicular to the first laser scribe.

Referring again to process 700, in FIG. 4A, after the third laserscribe, the bus bars are attached, process 750. Referring to FIG. 2, busbar 1, 640, and bus bar 2, 645, are attached. Bus bar 1 is often pressedthrough the second TCO and EC stack to make contact with the second TCOlayer, for example via ultrasonic soldering. This connection methodnecessitates the laser scribe processes used to isolate the region ofthe first TCO where bus bar 1 makes contact. Those of ordinary skill inthe art will appreciate that other means of connecting bus bar 1 (orreplacing a more conventional bus bar) with the second TCO layer arepossible, e.g., screen and lithography patterning methods. In oneembodiment, electrical communication is established with the device'stransparent conducting layers via silk screening (or using anotherpatterning method) a conductive ink followed by heat curing or sinteringthe ink. When such methods are used, isolation of a portion of the firstTCO layer is avoided. By using process flow 700, an electrochromicdevice is formed on a glass substrate where the first bus bar is inelectrical communication with second TCO layer 630 and the second busbar is in electrical contact with first TCO layer 615. In this way, thefirst and second TCO layers serve as electrodes for the EC stack.

Referring again to FIG. 4A, after the bus bars are connected, the deviceis integrated into an IGU, process 755. The IGU is formed by placing agasket or seal (e.g. made of PVB (polyvinyl butyral), P113 or othersuitable elastomer) around the perimeter of the substrate. Typically,but not necessarily, a desiccant is included in the IGU frame or spacerbar during assembly to absorb any moisture. In one embodiment, the sealsurrounds the bus bars and electrical leads to the bus bars extendthrough the seal. After the seal is in place, a second sheet of glass isplaced on the seal and the volume produced by the substrate, the secondsheet of glass and the seal is filled with inert gas, typically argon.Once the IGU is complete, process 700 is complete. The completed IGU canbe installed in, for example, a pane, frame or curtain wall andconnected to a source of electricity and a controller to operate theelectrochromic window.

In addition to the process steps described in relation to the methodsabove, an edge deletion step or steps may be added to the process flow.Edge deletion is part of a manufacturing process for integrating theelectrochromic device into, e.g. a window, where the roll off (asdescribed in relation to FIG. 2) is removed prior to integration of thedevice into the window. Where unmasked glass is used, removal of thecoating that would otherwise extend to underneath the IGU frame(undesirable for long term reliability) is removed prior to integrationinto the IGU. This edge deletion process is meant to be included in themethods above as an alternative embodiment to those listed above.

In certain embodiments, a different process flow may be used tofabricate an electrochromic device. Alternative process flows arefurther discussed in U.S. patent application Ser. No. 14/362,863, filedJun. 4, 2014, and titled “THIN-FILM DEVICES AND FABRICATION,” and inU.S. patent application Ser. No. 13/763,505, filed Feb. 8, 2013, andtitled “DEFECT-MITIGATION LAYERS IN ELECTROCHROMIC DEVICES,” which areeach herein incorporated by reference in their entireties.

Integrated Deposition System

As explained above, an integrated deposition system may be employed tofabricate electrochromic devices on, for example, architectural glass.As described above, the electrochromic devices are used to make IGUswhich in turn are used to make electrochromic windows. The term“integrated deposition system” means an apparatus for fabricatingelectrochromic devices on optically transparent and translucentsubstrates. The apparatus has multiple stations, each devoted to aparticular unit operation such as depositing a particular component (orportion of a component) of an electrochromic device, as well ascleaning, etching, and temperature control of such device or portionthereof. The multiple stations are fully integrated such that asubstrate on which an electrochromic device is being fabricated can passfrom one station to the next without being exposed to an externalenvironment. Integrated deposition systems operate with a controlledambient environment inside the system where the process stations arelocated. A fully integrated system allows for better control ofinterfacial quality between the layers deposited. Interfacial qualityrefers to, among other factors, the quality of the adhesion betweenlayers and the lack of contaminants in the interfacial region. The term“controlled ambient environment” means a sealed environment separatefrom an external environment such as an open atmospheric environment ora clean room. In a controlled ambient environment at least one ofpressure and gas composition is controlled independently of theconditions in the external environment. Generally, though notnecessarily, a controlled ambient environment has a pressure belowatmospheric pressure; e.g., at least a partial vacuum. The conditions ina controlled ambient environment may remain constant during a processingoperation or may vary over time. For example, a layer of anelectrochromic device may be deposited under vacuum in a controlledambient environment and at the conclusion of the deposition operation,the environment may be backfilled with purge or reagent gas and thepressure increased to, e.g., atmospheric pressure for processing atanother station, and then a vacuum reestablished for the next operationand so forth.

In one embodiment, the system includes a plurality of depositionstations aligned in series and interconnected and operable to pass asubstrate from one station to the next without exposing the substrate toan external environment. The plurality of deposition stations comprise(i) a first deposition station containing one or more targets fordepositing a cathodically coloring electrochromic layer; (ii) a seconddeposition station containing one or more targets for depositing an ionconducting layer; and (iii) a third deposition station containing one ormore targets for depositing a counter electrode layer. The seconddeposition station may be omitted in certain cases. For instance, theapparatus may not include any target for depositing a separate ionconductor layer. The system also includes a controller containingprogram instructions for passing the substrate through the plurality ofstations in a manner that sequentially deposits on the substrate (i) anelectrochromic layer, (ii) an (optional) ion conducting layer, and (iii)a counter electrode layer to form a stack. In cases where the counterelectrode layer includes two or more sub-layers, the sub-layers may beformed in different stations or in the same station, depending on thedesired composition of each sub-layer, among other factors. In oneexample, a first station may be used to deposit the cathodicallycoloring electrochromic layer, a second station may be used to deposit afirst sub-layer of an anodically coloring counter electrode layer, and athird station may be used to deposit a second sub-layer of theanodically coloring counter electrode layer.

In one embodiment, the plurality of deposition stations are operable topass a substrate from one station to the next without breaking vacuum.In another embodiment, the plurality of deposition stations areconfigured to deposit the electrochromic layer, the optional ionconducting layer, and the counter electrode layer on an architecturalglass substrate. In another embodiment, the integrated deposition systemincludes a substrate holder and transport mechanism operable to hold thearchitectural glass substrate in a vertical orientation while in theplurality of deposition stations. In yet another embodiment, theintegrated deposition system includes one or more load locks for passingthe substrate between an external environment and the integrateddeposition system. In another embodiment, the plurality of depositionstations include at least two stations for depositing a layer selectedfrom the group consisting of the cathodically coloring electrochromiclayer, the ion conducting layer, and the anodically coloring counterelectrode layer.

In some embodiments, the integrated deposition system includes one ormore lithium deposition stations, each including a lithium containingtarget. In one embodiment, the integrated deposition system contains twoor more lithium deposition stations. In one embodiment, the integrateddeposition system has one or more isolation valves for isolatingindividual process stations from each other during operation. In oneembodiment, the one or more lithium deposition stations have isolationvalves. In this document, the term “isolation valves” means devices toisolate depositions or other processes being carried out one stationfrom processes at other stations in the integrated deposition system. Inone example, isolation valves are physical (solid) isolation valveswithin the integrated deposition system that engage while the lithium isdeposited. Actual physical solid valves may engage to totally orpartially isolate (or shield) the lithium deposition from otherprocesses or stations in the integrated deposition system. In anotherembodiment, the isolation valves may be gas knifes or shields, e.g., apartial pressure of argon or other inert gas is passed over areasbetween the lithium deposition station and other stations to block ionflow to the other stations. In another example, isolation valves may bean evacuated regions between the lithium deposition station and otherprocess stations, so that lithium ions or ions from other stationsentering the evacuated region are removed to, e.g., a waste streamrather than contaminating adjoining processes. This is achieved, e.g.,via a flow dynamic in the controlled ambient environment viadifferential pressures in a lithiation station of the integrateddeposition system such that the lithium deposition is sufficientlyisolated from other processes in the integrated deposition system.Again, isolation valves are not limited to lithium deposition stations.

FIG. 5A, depicts in schematic fashion an integrated deposition system800 in accordance with certain embodiments. In this example, system 800includes an entry load lock, 802, for introducing the substrate to thesystem, and an exit load lock, 804, for removal of the substrate fromthe system. The load locks allow substrates to be introduced and removedfrom the system without disturbing the controlled ambient environment ofthe system. Integrated deposition system 800 has a module, 806, with aplurality of deposition stations; an EC layer deposition station, an IClayer deposition station and a CE layer deposition station. In thebroadest sense, integrated deposition systems need not have load locks,e.g. module 806 could alone serve as the integrated deposition system.For example, the substrate may be loaded into module 806, the controlledambient environment established and then the substrate processed throughvarious stations within the system. Individual stations within anintegrated deposition systems can contain heaters, coolers, varioussputter targets and means to move them, RF and/or DC power sources andpower delivery mechanisms, etching tools e.g. plasma etch, gas sources,vacuum sources, glow discharge sources, process parameter monitors andsensors, robotics, power supplies, and the like.

FIG. 5B depicts a segment (or simplified version) of integrateddeposition system 800 in a perspective view and with more detailincluding a cutaway view of the interior. In this example, system 800 ismodular, where entry load lock 802 and exit load lock 804 are connectedto deposition module 806. There is an entry port, 810, for loading, forexample, architectural glass substrate 825 (load lock 804 has acorresponding exit port). Substrate 825 is supported by a pallet, 820,which travels along a track, 815. In this example, pallet 820 issupported by track 815 via hanging but pallet 820 could also besupported atop a track located near the bottom of apparatus 800 or atrack, e.g. mid-way between top and bottom of apparatus 800. Pallet 820can translate (as indicated by the double headed arrow) forward and/orbackward through system 800. For example during lithium deposition, thesubstrate may be moved forward and backward in front of a lithiumtarget, 830, making multiple passes in order to achieve a desiredlithiation. Pallet 820 and substrate 825 are in a substantially verticalorientation. A substantially vertical orientation is not limiting, butit may help to prevent defects because particulate matter that may begenerated, e.g., from agglomeration of atoms from sputtering, will tendto succumb to gravity and therefore not deposit on substrate 825. Also,because architectural glass substrates tend to be large, a verticalorientation of the substrate as it traverses the stations of theintegrated deposition system enables coating of thinner glass substratessince there are less concerns over sag that occurs with thicker hotglass.

Target 830, in this case a cylindrical target, is oriented substantiallyparallel to and in front of the substrate surface where deposition is totake place (for convenience, other sputter means are not depicted here).Substrate 825 can translate past target 830 during deposition and/ortarget 830 can move in front of substrate 825. The movement path oftarget 830 is not limited to translation along the path of substrate825. Target 830 may rotate along an axis through its length, translatealong the path of the substrate (forward and/or backward), translatealong a path perpendicular to the path of the substrate, move in acircular path in a plane parallel to substrate 825, etc. Target 830 neednot be cylindrical, it can be planar or any shape necessary fordeposition of the desired layer with the desired properties. Also, theremay be more than one target in each deposition station and/or targetsmay move from station to station depending on the desired process.

Integrated deposition system 800 also has various vacuum pumps, gasinlets, pressure sensors and the like that establish and maintain acontrolled ambient environment within the system. These components arenot shown, but rather would be appreciated by one of ordinary skill inthe art. System 800 is controlled, e.g., via a computer system or othercontroller, represented in FIG. 5B by an LCD and keyboard, 835. One ofordinary skill in the art would appreciate that certain embodiments mayemploy various processes involving data stored in or transferred throughone or more computer systems. Certain embodiments also relate to theapparatus, such computers and microcontrollers, for performing theseoperations. These apparatus and processes may be employed to depositelectrochromic materials of methods herein and apparatus designed toimplement them. The control apparatus may be specially constructed forthe required purposes, or it may be a general-purpose computerselectively activated or reconfigured by a computer program and/or datastructure stored in the computer. The processes presented herein are notinherently related to any particular computer or other apparatus. Inparticular, various general-purpose machines may be used with programswritten in accordance with the teachings herein, or it may be moreconvenient to construct a more specialized apparatus to perform and/orcontrol the required method and processes.

As mentioned, the various stations of an integrated deposition systemmay be modular, but once connected, form a continuous system where acontrolled ambient environment is established and maintained in order toprocess substrates at the various stations within the system. FIG. 5Cdepicts integrated deposition system 800 a, which is like system 800,but in this example each of the stations is modular, specifically, an EClayer station 806 a, an IC layer station 806 b and a CE layer station806 c. In a similar embodiment, the IC layer station 806 b is omitted.Modular form is not necessary, but it is convenient, because dependingon the need, an integrated deposition system can be assembled accordingto custom needs and emerging process advancements. For example, FIG. 5Ddepicts an integrated deposition system, 800 b, with two lithiumdeposition stations, 807 a and 807 b. System 800 b is, e.g., equipped tocarry out methods as described above, such as the dual lithiation methoddescribed in conjunction with FIG. 4C. System 800 b could also be usedto carry out a single lithiation method, e.g., that described inconjunction with FIG. 4D, for example by only utilizing lithium station807 b during processing of the substrate. But with modular format, e.g.if single lithiation is the desired process, then one of the lithiationstations is redundant and system 800 c, as depicted in FIG. 5E can beused. System 800 c has only one lithium deposition station, 807.

Systems 800 b and 800 c also have a TCO layer station, 808, fordepositing the TCO layer on the EC stack. Depending on the processdemands, additional stations can be added to the integrated depositionsystem, e.g., stations for cleaning processes, laser scribes, cappinglayers, MTC, etc.

Although the foregoing embodiments have been described in some detail tofacilitate understanding, the described embodiments are to be consideredillustrative and not limiting. It will be apparent to one of ordinaryskill in the art that certain changes and modifications can be practicedwithin the scope of the appended claims.

Experimental Results

Experimental results show that the disclosed NiWNbO materials exhibitvery high quality coloring characteristics. In particular, the NiWNbOmaterials are very clear (transparent) in their untinted state, havingless color (particularly yellow color) as compared to other materialsthat are somewhat colored in their untinted states. Further, the NiWNbOmaterials show good switching characteristics over time. In other words,the switching speed does not significantly decrease over the life of thecounter electrode, as compared to certain other materials that exhibitincreasingly slow switching speeds.

NiWNbO Deposition

Mixed nickel tungsten niobium oxide, NiWNbO, may be deposited usingrepeated deposition of very thin layers of sputtered material as thesubstrate is rastered back-and-forth in a deposition chamber. Reactivesputtering of NiW alloy and niobium metal targets in a mixture of argonand molecular oxygen with a chamber pressure of approximately 10 mTorrmay be used. The NiW alloy target may be produced using a Hot IsostaticPress (HIP) method using Ni and W powders. The power to each target canbe independently controlled using two synchronized pulsed DC powersupplies. The ratio of Nb to Ni+W can be adjusted by varying the powerratio between the two targets. The thickness of the NiWNbO for a givenset of power conditions may be changed by increasing or decreasing thespeed of the substrate as it moves through the deposition chamber. Inorder to achieve the desired thickness of the entire counter-electrode,the number of passes in front of the targets is increased or decreasedas needed. The degree of oxidation of the film can be controlled byadjusting the partial pressures of Ar and O₂ in the sputtering gas, aswell as the total pressure. Through the manipulation of these processparameters, the ratio of NiW:Nb:O can be controlled. Heaters may be usedfor temperature variation, but the highest-performance films and devicesare typically deposited without additional heating. The substratetemperature is typically less than 100° C.

As an example, a high performance counter electrode may be achieved bysputtering in a pure oxygen environment with power and substrate speedsettings chosen to achieve a thickness of less than 5 nm per pass. Morethan 150 passes through the deposition system can be performed in somecases to build film thickness. The power supplies for the two sputtertargets may be chosen such that the NiW power (e.g., about 6 kW) isgreater than (e.g., about 12× greater) the Nb power (e.g., about 0.5kW). The resulting Ni:(W+Nb) ratio may be approximately 2.

OTHER EMBODIMENTS

Although the foregoing embodiments have been described in some detail tofacilitate understanding, the described embodiments are to be consideredillustrative and not limiting. It will be apparent to one of ordinaryskill in the art that certain changes and modifications can be practicedwithin the scope of the appended claims.

What is claimed is:
 1. A composition of matter comprising: (a) nickel;(b) tungsten; (c) niobium; and (d) oxygen, wherein the compositioncomprises an atomic ratio of Ni:(W+Nb) that is between about 1.5:1 and3:1, and wherein the composition comprises an atomic ratio of W:Nb thatis between about 0.2:1 and 1:1.
 2. The composition of claim 1, whereinthe atomic ratio of Ni:(W+Nb) is between about 1.5:1 and 2.5:1.
 3. Thecomposition of claim 2, wherein the atomic ratio of Ni:(W+Nb) is betweenabout 1.8:1 and 2.5:1.
 4. The composition of claim 3, wherein the atomicratio of Ni:(W+Nb) is between about 2:1 and 2.5:1.
 5. The composition ofclaim 1, wherein the atomic ratio of Ni:(W+Nb) is between about 2:1 and3:1.
 6. The composition of claim 1, provided in a layer having athickness between about 50-650 nm.
 7. The composition of claim 1,wherein the composition is formed through sputtering one or more sputtertargets.
 8. The composition of claim 1, wherein the composition becomestinted in response to an applied anodic potential.
 9. The composition ofclaim 1, wherein the composition is amorphous.
 10. The composition ofclaim 1, wherein the composition is provided as an amorphous matrix withnanocrystals distributed throughout.
 11. The composition of claim 10,wherein the nanocrystals have a mean diameter of about 50 nm or less.12. The composition of claim 11, wherein the nanocrystals have a meandiameter between about 1-10 nm.